dark background and substrate, feed hikari and shrimp with no head and tail but with the body shell on, low ph and high temp usually enhances their colour well, ohh and the ocassional live feeding makes them GLOW!!
As for the pellets vs feeders. I feed the feeder's Pellets right before I feed my bass. you can try that. And another ancient HCR secret is stuff your shrimp with the pellets as well. That way there getting all the nutrient's you want them to get. There are other little secrets as well but only after you have mastered the first two.