Make sure to vary your lure retrieve until you figure out what the fish are responding to that day. Sometimes they want a steady retrieve, but fish often respond well to some erratic twitches and pauses. Many times a fish will follow a lure but not bite. That extra twitch or pause can cause the following fish to react by striking.
Try using scent on lures, especially soft plastic lures which hold in scent. Even on other lures it can be useful to mask unnatural scents like sunscreen or bug repellent.
When fishing with sinking lures, vary the depth of the retrieve until you find where the fish are. You can do this but counting at a steady rate each time you cast and then starting the retrieve and progressively higher numbers. Once you find the depth where you get a bite, keep fishing that depth.
If your lure action is poor, try using lighter line/leader. Especially for smaller lures, the line diameter can have a huge effect on the action.
Trolling plugs generally need to run straight to work well. If a trolling plug is not running straight, you can often “tune” it by bending the eye ring slightly to one side or another with some pliers.
When fishing with crankbaits, try bouncing the lures off of rocks and other objects on the bottom. This can often trigger strikes.
As a rule of thumb, try more natural colored lures in clear water and brighter colors (chartreuse, orange, etc) in murkier water. On bright days start with lighter colors and on overcast days start with darker colors as they are easier for fish to see in those conditions.
Lure size and action matter more than color most of the time, so make sure you get those right.
Let the fish tell you what they want. Don’t stubbornly stick to a favorite lure or presentation even if it is not working. Fish can be very finicky, especially in highly pressured areas. Often they will respond to something they have not seen before when they are turning down regularly used lures.
Consider using lures with rattles in very murky water as it will help the fish find them easier. Conversely, in clear water rattles can sometimes spook fish.
In highly pressured waters or very clear waters consider scaling down your tackle, both in terms of lure size and line size. It’s amazing how large of a fish you can catch on a small lure sometimes.
Make sure all hooks are sharp on your lures at all times. If the point doesn’t dig into your fingernail, then take a file and sharpen it until it does.
If you are not sure whether you are getting a bite, set the hook immediately. If you stop and ask yourself whether or not you just got a bite the fish will be long gone. Except for some soft plastic lures, fish don’t usually hold onto lures for more than a second.
Many lures come with weak split rings and hooks. I’m not sure why; I assume it’s a cost saving thing. If you are fishing for fish that put a lot of strain on tackle, make sure you change out those split rings and hooks. To upgrade my split rings I like to use Owner Hyperwire rings.