If you are playing amplified there are a couple of things to make your vocals better. Actually, I can think of three things.

1) Learn good microphone discipline. This means staying on the mic. If you are moving left to right or back and forth you'll fade in and out and drive engineers (and the audience) crazy. In outdoor venues I keep my bottom lip attached to the mic, indoors two inches back. The only exception is that sometimes you may need to really "belt out" a line or phrase and the you need to pull back from the mic a bit. Only practice will teach you how much.

2)Good monitors that are adjusted so you can hear yourself. This eliminates the need to out shout the rest of the band. You can't sound your best when you are pushing to hear yourself. You need good info to know what you're doing.

3)Have an engineer that knows what your music should sound like . I've seen guys who work rock venues absolutely destroy other types of music. Be sure to talk to the engineer before you get on stage and tell him what you want. Good engineers are always accomodating.

Sing On!