TIPS ON... 
Gears:
    Your main objective when it comes to gearing a puller is to reduce the load on the motor, which means lowering the motor/gear ratio.
    While there are endless ways to gear your puller (aside from being limited by class regulations), worm gears seem to work the best for giving the most ratio reduction in the least amount of space.
    To get started, here's an example of a reliable gear arrangement for a Pro Tractor or 2WD:
Tires:
    This may sound silly, but you do NOT want a lot of traction. First, pullers are NOT allowed 'magna-traction' (defeats the purpose). Second, with good traction off the line, your truck or tractor will hop... or worse... simply pull the front up along with the pick-up system.
    Leave your tires 'slightly' dirty so that the tires can 'spin' off the line.

Weights, Balance, & Hitch height:
    Repeat after me..."The sled is not my enemy, it is my ally".
     Place all added weight as far forward as possible on your puller... this includes the motor. Now, use the SLED as your rear 'traction' weight. This is done by adjustment of the Hitch (hook). The higher you put the hitch, the more the sled will weigh the rear (experiment... you'll see what I mean).