Short answer: check out
http://www.usfirst.org/community/frc....aspx?id=10934
Slightly longer answer: FIRST pretty much tells you exactly what you need to do with electrical. They tell you what gets plugged in where, what needs to be protected with breakers (hint: everything!) and what size/type of breaker to use. They tell you what gauge wire to use for different parts. Follow the diagrams and instructions they have posted on the above page, and you should do just fine. Anything beyond that will require a pretty long and detailed response, probably more than you want to hear. There are different schools of thought with board layout, each with their pluses and minuses. There are tricks you can use to reduce the voltage drop over very long runs of wire. There are things you can do with custom circuits to make your life easier. I could go on.
There's one thing i would stress above all else with electrical: keep it neat and organized. If something stops working it's a lot easier to find the problem that way. Some teams have a huge mess of wires in their robot, and when something goes wrong it's difficult to find the connector that got pulled out.