Try to avoid the desire to simply start pedaling with the clips facing down when getting up to speed (the technique I often used as a kid). This will quickly lead to a lot of scrapes at the top of the clip.

Practice track stands. I don't even like to take my cleats out of clipless pedals at lights if I can avoid it (Look cleats are expensive, made of soft plastic, and wear out rather quickly when in regular contact with the pavement).

I'm a believer in the "pedal in circles" philosophy. This is one of the mantras espoused by Eddie B (Edward Borysewics, former U.S. Olympic Cycling coach) in his classic book, Bicycle Road Racing. However, I don't try to pull "up" so much as I try to pull "back" with my calves and hamstrings. At least thats how I visualize it in my head. I'm not sure that anyone contributes much to the pedal stroke from about the 9 o'clock to the 1 o'clock position.