12 strings are marvelous. If you want to hear a broad range of its potentional listen to (amoungst other things) bands from the 60's and 70's like The Seekers, The Hollies, The Merseybeats and, of course, The Eagles. Also, Peter Buck from REM uses a twevle string Rickenbecker on many songs. There's tonnes of things you can draw from.
Try some songs you already know, you'll be inspired to come up with new ideas.
As for tuning, Hootayah was absolutely right. I would look something like this:

Ee, Aa, Dd, Gg, bb, ee

Where the capital is the six string tone and the small letter is the octave.

I got distracted while stringing my tweleve string and ended up with

eE, aA, dD, gG, bb, ee

Has a slightly different sound. Something worth experimenting with!

Good luck and have fun!