Essays / Basic advises...for Clep Essay [7]

I am scheduled to take the English Comp w/ Essay and I would like to ask for tips for writing an aggree/disagree without coming across too much one way or the other.

I tend to be a very black/white person, either you are right or you are wrong
and I am worried about my response being too strong.

Any tips or general guidelines are appreciated.

Thanks
Kris