Surprisingly, there is some technique to it, and even more so if you want to be fast at it.
Take this guy for example:
He makes it look so easy!!
Fortunate for me, mine were never this bad:
But the key is to do it in one fluid motion like the first guy. I always seemed to have little "skip" before I jumped on. This totally slowed me down as I couldn't keep my momentum. It also left me in a weird position that had me constantly hunting for my pedals to clip in - again, more time lost.
This year I think I have it down. Don't jump onto the bike - SLIDE onto the bike. Makes a world if difference!!