On bright days use brighter colors. For night fishing use darker colors. Pretty simple. And if you are using chrome type baits gold for cloudy days, and silver on clear days. the light reflects better. Also if the water is very clear use more natural looking colors, not just the brightest and solid color worm. But in dirtier water it wont matter as much so use more bold colors because they will see it better. Another good tip -- Match the hatch. Meaning, if the fish are chasing bluegill during bluegill spawning, don't throw a crawdad pattern at them
hope this helps a little.
A little clarification, many people think that you should use brighter colors in the dark. this is a common misconception seeing as its a reasonable thought. But unless its glowing it wont do anything. If you hold something up to the sky in the dark do you see its color? No you just see black, so you use bigger and darker baits to get more contrast and make it bolder so it stands out more.
Sorry if this doesn't help much, Most of this is based off of bass fishing and i was not sure what you were going for, and I'm just a dumb 16 year old kid. But hey, maybe this will help you out a bit