As others have said, trolling for walleyes is most productive with worm harnesses or body baits. If you're not going to be using harnessed worms, minnows or leeches, the body baits should be of the long slender variety....something like ReefRunners in the 800 model. I don't think that actual colours mean a whole lot except that you should have dark and light on hand. Run your baits deeper than shallower. If there are floating or half submerged weeds, take a page out of the muskie guys' book by using a down rod. Most of the weeds will be caught by the rod and less time will be spent cleaning the bait, thus, more time in the strike zone.
I'm only a youngster but I hope this helps.