I am a singer who has accompanied himself on guitar for 40 years. A few things I have learned along the way:

* Mix up the order of your songs with different keys. i.e. try not to do 2 in a row in the same key, especially at similar tempos.

* Use dynamics in your volume to compliment the effectiveness of dynamics in your voice. bring it up. bring it down.

* Use a capo effectively to get different and more effective tones for a break.

* You try to give your voice personality. give your guitar a personality also.