If it is your first year in vex, something like this might be a good idea. It is very simple and not that bad in practice.
If you think you are better than that, look at the Catalogue of Drive Gearings and find a faster drivetrain.
Look at some YouTube robot videos from over the years. There are lots of team that give in-depth explanations of their robots.
If you need any more help, feel free to ask.