Old Folky,

Unfortunately, I don't have as much time as I'd like to respond at length right now.

See if you can look up threads from the last 6-12 months with titles like "Right-Hand Technique," "Folk Song Accompaniment," and anything including the word "Fingerpicking." I'll try to look 'em up later, if and when I can, or maybe a nice helpful MudElf/JoeClone will provide a list of related threads at the top of this page (as so often happens). If you find some of these threads, you'll see that I have plenty to say on this topic; look for posts by M.Ted and Patrick Costello, too, among others. Hell, read the whole threads and make your own decisions about whose advice is best for you..

Highlandman (above) was absolutely right about the "G" chord, but he was wrong about having to damp a string. You can get the whole 6-string chord easily enough like this:

E--pinky on 3d fret
B--open
G--open
D--open
A--middle finger on 2d fret
E--ring finger on 3d fret

Like you, I play mostly in C and G. In both keys, if you use the above formation for the G chord (along with the C and F, or the C and D chords), you can hit plenty of melody notes with your pinky on and off the 3d fret, and with your forefinger on and off the first fret, of the top 2 strings. Also consider using the alternate D/D7 chord formed by sliding the C/C7 up two frets, again, with and without the pinky fretting the high-E string at the 3d fret (or in the case of the slid-up D, the 5th fret).

Learn to play Freight Train, and you'll learn a lot about playing melody notes in C along with a steady alternating-thumbstroked bass. Learn a few Mississippi John Hurt songs in G and (especially) C, and you'll learn a bunch of riffs you can use in other songs in these keys.

More later ~ or if not, more elsewhere, in those past threads I mentioned above.

Have fun.