I do Singles too! Although lately I prefer Doubles. There's some crossover between the two formats, but the Pokemon that tend to do well in Doubles are a bit of a different breed... and Spread, Speed Control, Priority, and Guard moves all take on a pretty different light. It's uncommon to see hyper offensive teams (at least in my experience) because it's pretty easy to shift the momentum out of their favor in a couple quick moves.
So I'd start playing Battle Spot Doubles (or me) with some of your bulkier mons to see what you like to use, then experiment with team synergy and moves beyond that.
We have a great resource that opened up here recently that I've been referencing as I get better at Doubles:
http://www.pokecommunity.com/showthread.php?t=344601