"No" is only beginning to be meaningful at your son's age. He can tell, from your tone of voice, that you don't like something that he just did. But that's still a long way from understanding WHY something is wrong. And once the power of "NO!" really gets through to him, he'll start using it all the time (a period commonly called the Terrible Twos). Some kids also include the slaps/hits they were exposed to.
Many parents have discovered that the more they can find a mutually agreeable way to get to "Yes!", the happier and less stressful toddlerhood is for both child and parent. Here's my list of favorite parenting tips. I've collected these ideas for years from my own experience and the terrific outcomes I see with lots of other parents:
(I last rewrote this for a little girl request, and don't have time to do that again for a boy – please read with this in mind.)
1. Child behaviorists make a very compelling case that ALL behaviors are strategies to get some need met. When she's acting out, your daughter is feeling some need that is not being met by current circumstances, and the more carefully you can ferret out what she's feeling, the more likely you are to help guide her toward better behavior.
2. Keep in mind that personality does make a difference. Some kids are definitely more intense, more demanding, more needy or bossy or energetic than others. Children, particularly the more intense and demanding ones, must have opportunities to gradually learn to deal with disappointments.
3. You can't "make" a child be happier or more easy-going, but you can often manipulate their experiences so they are less frustrated. This is a very difficult age for most kids, who want to do/try so much more than they are able. They are limited by motor skills, by basic comprehension, by language skills, and by rules and schedules that they have no say in controlling.
4. Very few 2-3yo's have any real idea how to share. They may tolerate having things taken from them, or being required to hand over toys to other kids, but that's not the same thing as understanding the reciprocity of sharing. Also, many toddlers are still at the stage of "parallel" play, playing alongside other littles (and perhaps grabbing their toys), but playing "with" will only begin to develop gradually over the coming year or so. Find opportunities to play sharing games with your child, and make the takings and givings-back very brief at the beginning so they have a chance to see the loss of some toy as a permanent, heart-breaking situation.
5. Trust that she is not "trying" to be naughty. Children don't really want to cause problems or get in trouble if they have any other way at all to meet their own growing need for autonomy, independence, and control of their circumstances. She's simply encountering many new experiences that she does not yet have the life experience to handle yet. It will be a while before she sees very much from your point of view. As exasperating as that is for adults, she can't help it. It's just reality, and reality is easier to take if you can accept it. (That can be harder to do if you have other adults pressuring/judging you about your child's normal behavior.)
6. Digging in heels and tantrums are a natural outcome of becoming more frustrated than the child is able to endure. This "new" behavior may seem to come out of the blue. It's more often true that the child is tired or hungry, or simply overstimulated or over-scheduled. The stress of travel, teething, changing schedules, illness, or any major change, may contribute.
7. When she wants something, empathize. Big time, and in the child's language. I love the advice of Dr. Harvey Karp on how to get on a tantruming toddler's wavelength in this and several related videos: http://www.youtube.com/watch?v=G6KnVPUdEgQ&featur.... . Once your little girl realizes you do care about what she wants, she's more likely to be able to calm down and cooperate with what you need from her. And there are lots of positive ways to approach this, rather than just saying no. They hear no so often, and they can be so frustrated by it. And they learn to tune it out. So look for ways of finding a mutual "yes," as in "Hey, look at this cool toy," or "Can you hop over to me like a bunny?" instead of "No, don't touch that," or "Stop that and come here right now!" Try to save "no" for those occasions when children are trying something dangerous.
8. Keep it playful. Children learn primarily through play. You may need help with this if your parents didn't model a lighthearted and cheerful approach when you were little. The book Playful Parenting is a great resource. Your daughter's sense of humor is developing, and you'll both be happier if you can nurture that. (Also be aware that some "behaviors," like throwing, are a natural experimental activity for kids, a form of play that is programmed into them for the purpose of developing brain/body connections. It's a very strong impulse. Find plenty of "acceptable" play outlets for those repeating behaviors, like throwing things into a basket. And remove things that you don't want them to throw.)
9. There will also be times when you must have her cooperation, like diapering or trips to the store, so keep a special toy that she gets to play with only at those times or keep her as playfully engaged in the process as possible. This often requires creativity, because each child is different. (For my grandson, we came up with a series of plastic jars in which he could see, shake and rattle different small objects, buttons, mini-toys, marbles, nuts and bolts, etc. These would keep him interested long enough for a diaper change, even though he would rather be on-the-go.)
10. Here's a big one: give ADVANCE NOTICE when you'll want her to be doing anything differently, especially when she's grooving on her activity/play. All children absolutely hate abrupt, unexpected transitions (and so do most adults). With my grandson, we let him know at least a couple of times that a change is coming ("We're going to go to the store / have lunch / take a nap pretty soon." … and then a second or third alert one minute before making the change.)
11. Whatever the next activity is, make it sound as desirable as possible. Give some detail about the ride in the car, or a favorite food at lunch, or sweet snuggles before nap. Be positive and enthusiastic. Be calm. Be "as inevitable as the tides." Desperation will show, and even though she's too young to deliberately plan a power struggle, she will quite naturally sense any cracks in your resolve in an attempt to meet her own emotional needs. And this is where future power struggles truly can begin.
12. Try to keep demands low when she's tired, over-managed, hungry, or sick. An already frustrated child doesn't have any emotional reserves left with which to cooperate. (Often true for adults, too!)
13. Get to know her most likely trouble-spots, try to see them from her point of view, and plan ahead. For many kids, it's when they want something they've seen. So keep those things out of sight when possible – so many parents think they can just leave tempting objects sitting around. This is one more source of endless frustration for kids, so child-proof your home. And for those things that can't be kept our of sight, be prepared with a distraction – for example, a toy she likes when you have to take something away from her, or a healthy treat when she wants a sugary snack. Laughter, introducing a new game, a few twirls and bounces, hugs or tickles, a goofy song, can help break into her determination to get something she wants (that short attention span is both a curse and a blessing).
14. Avoid bribes, but let her work toward occasional rewards. Don't try to "buy" cooperation for things she must do anyway with "IF you'll do X, we'll let you have Y." Instead, phrase it as if she gets to assist in advancing something good for herself: "Hey, as soon as you help me get X done, then we get to do Y." It sounds like a small distinction, but it's important. It gives the child a chance to cooperate in what feels to her like choice, even when there's no "if" about it.
15. Be sure she gets lots and lots of physical activity during the day. Time outdoors in nature is calming for most children. If she has pent-up energy, it will have to come out some way, and unless channeled in a positive direction, it will likely to add to both her stress and yours.
16. Whatever you are trying to teach will need to be repeated hundreds of times over the next few years. That's completely normal. Attention spans and impulse control are extremely limited in toddlers. It takes time, attention, and repetition to build new habits. Look at your parenting contract, and you'll find it in tiny print under "I agree to the following terms and sacrifices."
17. Spanking and time-outs don't work for every kid, and will sometimes actually backfire over time. Especially with spanking: children may be shocked, scared, or shamed into cooperating, but behaving for the sake of avoiding pain isn't the same thing as developing an internalized sense of "good." Consistent, calm guidance and demonstrations of what you DO want from her will work better in the long run than punishing for what you DON'T want her to do. For example, kids learn without punishment to use good manners when their parents speak to them with respectful good manners. See more on this by googling The Science of Parenting or Emotion Coaching.
18. Pay attention to what you love and appreciate about your daughter, and make sure she knows. Remind yourself to do this even when you're tired or busy. Children CRAVE attention and approval, and if she knows you're noticing her finer moments, she'll try to create more of them. If she doesn't get that positive notice from you, she'll seek attention in other ways, and that often turns out to be misbehavior, because you notice it.
This stage won't go on forever, and most kids emerge, like butterflies from a cocoon, into a new, more mature version of themselves by the time they are around 4.5 or 5. I hope you find a great deal of pleasure in this unique time in your daughter's life.
I hope these tips address some of the challenges you're seeing in your daughter. Your friend is right about one thing: children need IMMEDIATE and consistent response from parents after every offense.
But EVEN MORE SO after every good, helpful, polite, cooperative or voluntary thing they do. The positive messages have to outweigh the negative ones 20 to 1, or a negative spirit can take hold in that child, and they become less enthusiastic, less hopeful, less positive about their future possibilities, and less motivated. Life becomes an ongoing, joyless chore. They begin to see themselves as bad, or perhaps even unlovable. Many children begin acting out their negative self-images by the time they are 4 or 5, and it only gets worse as they grown up. Other authority figures become symbols for their parents, and they transfer all the resentment and disappointment they feel onto the world at large. These sad outcomes are what I learned at my mother's knee. Or perhaps I should say, over my mother's knee.