First of all, I buy trolling rods/reels in sets of 2. That way when trolling and you figure out the bite, you can put two exact rods/reels/lines/lures in the water and double up. Buying the exact same set up allows you to reproduce (down to the extreme detail) what works.
I have two Shimano TR 200-G's on Diawa Heartland Walleye Trolling rods. The reels only hold about 8 colors of 18lb leadcore but I bought them sight un-seen and will use them until I get a better deal elsewhere. I have about 20 yards of 20 lb test mono backing just to prevent the mono from slipping and I use a 10-15 foot leader of 10lb mono (join the lead and leader with a double uni knot).
One of the most important things is a clicker and drag that works well. Lead has no stretch and the 15ft of leader does not stretch much so a good drag is important to keep the fish from throwing the hook. Another thing is a soft tip rod and when a fish is hooked, keep the rod tip high and let the rod take the surges.