Avril. Tape record your practicing at home, analyze how you sound, like going out of tune, etc. Really, a voice teacher is what you should find, if you naturally don't have good tone or control, you REALLY need someone else to guide you in what to do to get it. Listen, listen, listen, to your own voice on tape in private, and correct what you can.
Memorizing lyrics is very important.

Alice in Montana, USA