Eechay, I am also a singer who just wants to be able to accompany myself, but not sound boring on the guitar. First thing...choose terrific songs. They need little imbellishment. The advice to change key is good, if you are going to present one song after another. Fiind a key that lets you pick out the melody (or harmony) to what you are singing, at least somewhat, then play in that key, even if you have to capo. Make what you do know on the guitar work to your best benefit.