The Rapala is a must have for any serious trout fisherman. There isn't a more exciting way to caught a trout than on a crank bait.
Floating: Performs best in slower water, across the current or against the current. Does not work with the current. Its too light. When you cast this out, let it hit the water and rest. After a few seconds give it a twitch. If that does work and you crank in it at a steady pace or give it quick jerks, usually two at a time.
Sinking: Performs best with the current. Cast it upstream and begin to reel it in before it even hits the water. You don't want any slack for it to be swept down. Real in as quickly as you need to, so that it keeps the line tight. The sinking is more difficult to fish because it does sink and its possible to get caught up on rocks. Its worth the risk.
These baits are expensive, but there is nothing else like it.