Learning to playbluegrassmusic on my guitar,and learning how to sing bass......

Most of the bluegrass is in your thumb, you play the bass strings with your thumb, and leave the rest of the job for the rest of your finger. Johnny Cash and Mark Knopfler are the two dudes who opened my eyes to bluegrass rythms. Also Johnny Can help you a lot on those bass tones try singing daily as deep as you can but don't stretch it out, just as much as you feel comfortable everyday and after a while you'll get the Barry White kinda bass sounds. And for the bluegrass thing just check the internet out there are tons of high quality in depth reviews of the thumb picking style, and try playing to a four bar backing drum track and follow it up with your thumb. And that's the rule of the thumb.
Common Bluegrass Flatpicking Licks Guitar Lesson Tutorial