Answer:
There are many factors that come into play when fishing rapalas for trout. In general it's a match the hatch thing with size , color and depth being the key. Usually dark colors in the early morning with sinking or countdown lures working best. If the weather is cold or if the water is 45F or below use countdowns (CD3, CD5, CD7) in natural bait colors preferably with red or orange bellies. As the sun rises look for rising fish. This can indicate that it is time for using the floating lures. I prefer orange over yellow or perch pattern floating rapalas (F3, F5, F7, F9). If you are trolling, speed is also a factor. Remenber that the faster the boat moves, the deeper your lure presentation will be. Start with a very slow troll and vary your path fishing an area in wide "s" patterns. Larger, more aggressive fish will tend to bite a faster moving lure. Also when trolling, monitor the amount of line you let out. Start with 100 feet and if necessary not more than 200 feet. The more line you let out the closer together your rapalas will ride in the pattern and the greater chance of creating a very special rapala tangle. If casting for trout find and area where the fish are working. Cast beyond the fish and "rip" the lure in several quick jerks while varying the speed of your retrieve.
So the best colors?...... For countdowns: Green over red or orange, perch, sometimes pink or rootbeer. For floaters, orange over yellow, perch, chartruse, or chrome.