Ton of good advice so far.... yeah watch your hard constanents (p's & d's). Might try these tips I've learn over the years:

1. I will control volume & tone through proxiemity (distance) if you need to sound more bassy and thick- get closer

2. higher notes push more air and you'll be louder pull back from the mic to maintain the same volume level.

3. substitute p's for b's- example- sing "beople" instead of people, in other words use a softer constanant. Can the audience tell the difference? No (especially after the first beer!)

4. Here's a major mic secret, I use this in recording when there is no compressor to be seen:

sing right beneath the mic, instead of directly into it, it will virually will be pop free... course I'm not the first one to spit this secret out... it really works!

Good Luck!