Some good tips so far!
I, too, have done lots of traveling with my daughter alone (till she was 3 years old, when we added her little brother - and the 3 of us have taken a couple of trips, too).
1) If you're not used to toting a stroller, try a baby carrier (like Baby Bjorn), and a backpack. This frees up both hands for a piece of luggage (or two) to lug behind and the diaper bag over the shoulder. Try it at home - it's more comfortable than you'd think, because of the weight distribution!
2) If you can, plan a longer layover - ideally 2-3 hours. This will give you and your LO time to stretch, eat/diaper change/outfit change (if any issues on the first flight...), plus, if you have a delay with your first flight, you will hopefully have enough cushion so that you don't have to stand in line waiting to change your second flight. (That is the WORST with a LO or two...)
3) This sounds odd, but avoid hot drinks. I witnessed a frazzled mom at a gate once who was trying to juggle some luggage and coffee but lost her grip on the coffee cup, which promptly fell onto her toddler's shoulder (she whisked him to the restroom, but had to leave all of her stuff. He ended up ok, as his shirt absorbed most of it, but I can still hear his initial scream...). I try to stick with bottled water - no spill, no burn, no mess.
4) I was REALLY nervous about my first flight alone with my 3 year old and 6 month old. I took pictures of them wearing their "travel" outfits - smiling, not smiling - to carry with me, in case I lost sight of one of them. The plan was to show the nearest airport person and say "This is what they look like and what they're wearing!" (Luckily, I didn't have to use them, but I did feel better having them!)
5) Definitely plan on having your LO nurse (breast or bottle) during take-off and landing to help the popping ears. (I've only had one instance of an ignorant (male) flight attendant who told me I couldn't, but I have never had any more problems.) When the kids were old enough I brough baggies of kind of a trail mix - Kix, Cheerios, Chex, pretzels, Cheez-its, raisins. Don't feed your LO sugary stuff (I've seen parents give Mtn. Dew and Fruit Loops!??) and expect her to stay still on the flight. :-)
6) Don't let others bother you, if you feel your LO seems a little more cranky than normal. You may feel like everyone is staring and annoyed, but most other travelers have been through this themselves. I try to stick close to other moms w/ kids at the gate, restaurant, etc. Plus, we tend to watch each other's backs (and kids' backs!).
7) Try to limit your luggage (and smaller bags are easier to maneuver than bigger ones). Are there items you can purchase once you get there? (I usually carried just a day's worth of diapers and purchased the rest locally.) If you are meeting someone there, they may be able to purchase items for you in advance (especially liquids - shampoo and such). Forego the towels if there are some where you'll be staying, etc.
That's all I can think of at the moment.
Hope the trip goes well!