Research, Citations, & Plagiarism

I do not have problems with the research and plagiarism part of this discussion.  I am quite confident that I can research and avoid plagiarism.  What I have problems with is citations.  I am not sure how to resite or when to place it in a paper.  I struggle with this area.  I do seem to get it right but I am often worrying if I am doing it right.  What also gives me such grief is the reference page.  I am always confused about that page.  I know we put it in alpha order and stuff but how to do it correctly is what gives me trouble.  I have lost points on past papers due to referece page.  Any suggestions would ve glady appreciated.