Watch the Travis Picking online guitar lesson by Joe Dalton from 50 Country Guitar Licks You MUST Know
You can devote your entire life to studying Travis picking. Obviously, check out any Merle Travis you can find. Chet Atkins also played many solo pieces in this style. You will hear this rhythm pop up from time to time in popular country music. Get that thumb pattern happening like it was second nature. This is the key.