First is the color temp and CRI of the bulb/chip; make sure they match your application. Sometimes mixing bulbs/chips works well to get a more pleasing & usable spectrum. I've also found that the strip LEDs with multiple colors and a tunable controller produce good results.
Second, find a power supply/controller that has a very high frequency. LED's don't inherently flicker, and when powered straight from a source like a battery provide a completely steady light. The flicker is typically from a time-chopping brightness controller. Cheap ones may use 60Hz, which the eye can still see, especially in the peripheral vision areas (rod cells, sensing only grays detect motion much better, whereas color-sensing cone cells at the center of the visual field have a slower response so detect flicker less well). Ideally, get a controller well above 25KHz to also eliminate any audio artifacts.
I'd very much like to see someone more expert chime in!