Checked two of his songs. Seems to prefer the key of C, Lot of I-vi C to Am
I'd suggest you lay down a basic C F G progression and see where that takes you. If in doubt thrown in an Am then back to C.
http://www.ultimate-guitar.com/tabs/...yolas_tabs.htm
Found the lyrics, but can not get the site address to stick. It is a basic 8 line verse with a 4 line chorus. I'd start out with a C F G7 C for each two lines of the verse and flesh out from there.
Have fun.