Fish the Northe half of the lake (you'll pick up fish in most places up there), and use 2-3.5" tube jigs (white, smoke, chartreuse - skinny ones or fat ones) on 1/4 oz. jig heads, tipped with a small piece of sucker meat (get suckers at Jax or Dicount in Fort Collins, or at Sportsman's in Loveland). You can try other things as well, but the above will get you a lake trout or two, most likely.