Just a quick tutorial for dungeon masters using the roll20 virtual tabletop on how to assign tokens to your players, so that they can edit their health and track their armor class through the token without having to constantly stare at their character sheets.
One thing I forgot to mention was that you can adjust health on the token by simply entering in the value with the addition or subtraction symbol in front. For instance, if your token takes 5 damage, and they're at 20 health...highlight the 20 in the bar, and type "-5" in place of it and hit enter. It would do the math automatically and return a value of 15.
This is especially valuable for the DM's who may have to keep track of health for up to 20 tokens at a time, but it also works for players.
Also, keep a cheat sheet on the virtual tabletop. Hide text on the GM layer reminding you of traps, disarm DCs, loot contents, and various other location information so you don't have to slow down the narrative referring to physical notes. It's a great way to help you keep the pacing so your players don't space out.
Good luck!