I just bought LA Looks' Wet Look Gel -- yah, the cheap stuff! It works well! But I get the best results from TreSemme.
I do have to use a lot of product, though--my hair is very thick, coarse, and curly--girls with finer hair may not need as much. My method: I comb my hair in the shower while it has conditioner on it, then get out and while it's still dripping I apply a frizz-fighting serum (any brand will do, it' s all just silicone). Then I take handfuls of the gel and apply carefully to each section of my hair. I work very quickly to handle the hair as little as possible, and make sure to apply product both underneath and on top. I concentrate on the ends as these tend to be very dry, and on the crown to stop frizzing. I usually pull the bangs down hard across my head so they'll dry smooth, too.
As long as I thoroughly coat it, and don't touch it while it's drying I get a beautiful wet look. (I never get it perfectly, there is always some small dang patch in back that gets fuzzy no matter what I do! ARGGHH!)
TreSemme Curl Care Mousse gives me a fantastic wet look, but I have to use a lot of it.