1.) Have decent looking bumpers that match the FIRST color scheme, using the recommend material is best as well. Good bumpers do not make good robots but at competitions you can usually get a feel for a robot by looking at its bumpers.
2.) Watch Karthik's presentations.
http://www.youtube.com/watch?v=Apk_X-maRf8
http://www.youtube.com/watch?v=smWy7FQ8jLE
Pay attention to his section on strategic design, especially in the 2012 one. He talks about many ways to make a competitive robot without many resources. The example that he uses is that in 2012 having a small robot that could balance well on the bridges was more valuable in most regional play than a less than mediocre shooter. Follow his priority list idea. It's simple, but it works.
3.)
Read the manual! Read the manual! Read the manual! Read the manual! Read the manual!
If you don't know the rules you aren't really playing. Think of that friend that wants to play Settlers of Catan, even though you don't know how, that says he will just explain the rules as he goes along. It's no fun and really hard for both of you. Learn the rules before you play.