Watch the Alternating Bass online guitar lesson by Muriel Anderson from 1-2-3 Fingerstyle Guitar
You'll get used to the distance between the strings as you rotate your thumb back and forth between two strings.
Use these exercises to listen to and adjust the amount of muffle or detachment of the bass notes, really nail the groove, and play loud! Just the volume itself combined with very precise tempo and crisp sounding bass will give energy to your playing. Playing with recordings or playing with other people is more fun than only playing with a metronome.
Try some of each.