Hi C.,
When my second was this age advice from a friend worked brilliantly. We gave him board books to look at and gave him only a little bit of light to see by. He would look at all his books and get sleepy and fall asleep on his own. So basically if you can get them to sit still long enough they will fall asleep. I think this worked because he loves books.
My third is far more high energy and not so interested in books. We tried everything and nothing worked except staying right with him, some days he just didn't sleep. So, we gave up naps at about 2 1/2 yrs. Like the others say, he goes to bed a lot earlier and without the hassle. But when we can see that he is tired, we give him a nap, about 1 or 2 times a week. The downside to this is that if they are too still after about 3 o'clock, like driving in the car, they will fall asleep. I find that it's very difficult to wake him, he rarely wakes up happy from a nap like that and of course now bedtime can be more difficult.
Now I realize that we had a discipline issue (meaning he doesn't want to obey and we weren't making him). We are working on that with timeouts and keeping him close, basically being more consistent throughout the day, giving him play areas (boundaries that he has to stay inside) where ever I am working.
One key that I know of to nap time is that there is a good window of time (about 15 minutes, usually happens around the same time everyday, if they have a regular bedtime and waketime) when they are getting tired and showing signs. You have to grab them and get them to bed then, that will be the easiest time to get them to sleep even if you have to stay with them.
We've gotten a lot of good info from the Babywise series by Gary Ezzo, for this age it's called Toddlerwise. The main idea is that you're the parent, you get to decide what's best for the child, while considering the family, so not letting the child run the show. I found that just having this confidence helped to put my child at ease and trust me more easily. So, it doesn't become a battle, it's just a matter of I'm the parent and you're the child. I love you, so I'm going to take care of you and do what's best for you.
The other thing that they say for this age of child is that if we haven't trained them in first time obedience (like do not touch, stay in bed, etc.) that we will have trouble with potty training. I guess that's when I realized that I had a problem, when I started with the potty training and had so much trouble.
Hope this helps. All the best.