[Al Skierkiewicz]

From an electrical standpoint...
1. Make it efficient so as to use less current.
2. Make sure the motor leads are tight, solder when you can, which should be everywhere.
3. Dress the leads so that they won't get caught in the drive train or be run over.
4. Make it efficient so it won't overheat.
5. Dress the leads so they won't be bent or pulled when the robot steers to left or right.
6. Make the wiring as short as possible so you can minimize the resistance and therefore the voltage drop.
7. Make it efficient so it doesn't burn up the motor or the speed controller.
8. Test, Test, Test. check the current delivered to the speed controllers under all conditions, especially turning.
9. Make it efficient. (Can you tell I like this one!?)
10. Make it easy to repair or replace the motor, else make the system modular and have replacements.
Good Luck