This is a big topic but I’ll tell what works for me and what I am most familiar with
The three most common types of crank baits are wide slow wobble (these are your fatter / rounder crank bait) Tight wiggle ( Minnow type crank baits) and very fast vibrating crank baits (Cordell spots and other lipless style). Then for most types, you have different sizes and have different running depths
As in any type of fishing, you want to try and mimic what the fish are feeding on.
The best thing you can do is find some real clear water and play around to see how your actions cause a reaction in the bait. Then you can visualize what the bait is doing when it's in the strike zone.
Most of the time crank baits are targeting actively feeding fish. When your after feeding and active fish, you have to find what they want in the way of retrieve. I like the super slow retrieve of a rebel crawdad 5-7 foot crankbait. Reel it slow and you can feel the throbbing of the lure. If that does not work, try faster, Try stopping it try burning it or try all three in one cast.
If the they are not very active and not feeding hard, then you want to look for a reaction strike, Bouncing it off rocks and bottom or trees etc etc,, the lure will become erratic in its motion and that often will trigger a strike. Again, mimic what you think they are feeding on.
As an example, on Horsetooth the other day, I was fishing the damn. I caught a smallie on a small grub. When he came up, he tosses a crawdad that was red and white colored and about 1 ½ inches long. Since the wind had come up and jig fishing was getting tough, I started tossing a matching color rebel crawdad lure with a steady slow to medium retrieve and just caught a ton of 10-12” smallmouth and was getting bit on almost every cast.
Schooling fish like wiper, Burning a lipless crank bait through a school of them can be awesome.
Trolling minnow type baits can be very productive as well as casting and retrieving them in a jerky motion with a stop and go method.. X-Rap and Husky jerks fall into this category.
Sounds like your trying the right things. Fishing can be frustrating at times but when you nail it, It can’t be beat.
Keep experimenting, the only way to catch them fish, is for you to read what they tell you.
Brett