Alot of it is practice and experience; keep doing it. Probably one of the most critical points is starting off right, especially acapella as I do. Getting the first few notes right is pretty esential, so get the practice in, in the bathroom, with a few friends and see if you can find a quiet corner to practice the opening verse. You can either close your eyes or focus on a point on a wall. Try not to rush it. It is always well appreciated when someone new begins to sing publically, and the audience does not mind the quality of the performance as much as the fact that one has made the effort. I have been encouraged in this way to sing even more songs. Two new ones (to me)I will be singing tonight are McTells Let Me Down easy Baby and Rusby's My Young Man. I have the words in front of me as my security blanket. I get a buzz out contributing rather than just listening.