Crankbaits can be used to cover any depth of water from the top to extremely deep. A big Redfin cranked slowly on top so it leaves a wake is deadly on winter stripers at night on some Georgia lakes. A Mann's 30 + will dredge the ledges in thirty feet of water. And if you want to go any deeper, rig a floating Rapala Carolina style with a three foot leader above a one ounce sinker. You can drag it through the deepest holes and catch those fish that are holding there.
When trying to decide on a color to use, don't be too timid. A wide range of colors will usually work. Check with local marinas or fishermen to see what is favored on a particular lake. Generally, in clearer water use more natural colors and in stained water use brighter colors. A dark crankbait will also show up well in muddy water or at night. Give several colors a try and let the fish tell you what they want.
Size of the bait you choose is important. You may have to go to a big bait to fish deep, but otherwise try to "match the hatch" by using a crankbait about the size of the food the fish you are after are eating. If the bass are feeding on tiny threadfin shad, use a tiny Rat-L-Trap or Tiny O or #5 Shadrap. If they are eating big shad, go with a bigger bait. Fish often lock in on a size and will not hit something much larger.
Shape of bait can be important too. A shad shaped bait is better than a long, thin lure when the fish are eating shad but a thin bait will attract more bites if the fish are eating minnows. Be observant and watch what the bass are doing to help you decide.
The best plan of attack for the beginner crankbait fisherman is to get several sizes of the same crankbait, in a couple of colors. Norman's N series, Shadraps and Mann's + series are all good examples of the type you can get to meet any needs. You can then add to your collection as needed.
What ever you choose, make sure the hooks are sharp. Dull hooks will not stick into the fish and will not hold it. Sharpen your crankbait hooks with a sharpener or a file. Use a split ring or good wire snap to connect your line to your bait. Either will allow the bait to swim freely and produce the action it is designed for.
Fall is an excellent time to fish a crankbait. Bass are gorging on shad and crawfish getting ready for the coming cold. Fish a shad colored crankbait or crawfish colored crankbait around secondary points in the mouths of coves for bass. Try trolling a deep running Rapala or Thunderstick for stripers, or cast a topwater version at night for them.
Crankbaits deserve a place in your tacklebox and on the end of your line. They are the most realistic looking baits you can use, imitating a baitfish more closely than other baits. You can't catch a fish on them unless you give them a try.
If you have a favorite crankbait, or a special way of fishing them, let me know about at firstname.lastname@example.org.