Hi. Does anyone know how to improve the higher notes? My lowest is the low E on a guitar and my highest is around the 16th/17th fret on the high E. The notes from the 12th fret on the high E sound weak and sorta distort. I know I can definitely reach them. On a good day I can and they sound fine. Then after a while I can't again. Is there a way to improve them? Like to keep a consistancy going? Thanks.

EDIT: Yes, my voice has broken and settled long ago so it's not that. :P
Well as "self trained" sorta singer one helpful thing I found was just simple scales and exercises. Like for example hit a note on piano or guitar and then go up the notes of the scale keeping in mind the dropper half and whole steps of the major scale. I try to do this exercise using different syllables instead of just naming them using solfeggio (do re mi , etc.). Proper breathing also helps and although my breathing could use improvement I've been told that you don't want your shoulders to raise when you breathe. Hope this helps.
As a singer myself, I would read some books on technique, or see a singing instructor. This is a guitar site and even though some people could give you some good information, you never know if its good or not. Your voice has an almost direct correlation with your health whereas if you mess up a guitar, you wouldn't be risking quite as much. Check your sources and don't rely on the internet for singing.