Conversely, if you decided to wait for an afternoon flight, and there are delays earlier in the day, your flight time is likely to suffer.
Plus, if you plan for an early flight and there is something that causes it to be canceled or delayed, you have more time to find an alternate flight.
No. 1: Don't check your bags
This is an air travel gem that's been around for a while, but it is worth repeating -- and listening to: If you can do it, don't bring any checked baggage. Just bring a carry-on (make sure its dimensions fit the airline's requirements) and don't worry about bringing checked luggage.
This will save you time checking in. It will save you time waiting at the luggage carousel. It will save you hassle if your bags are lost or sent to Topeka.
True, you can't bring everything in your carry-on, so you have to pack strategically. Also, remember the limits on liquids and gels.
Also, given the fact that airlines are charging for checked baggage, you can save a few bucks by simply bringing a carry-on.