in guess, to start off with, look at what answers youve done (trials, midcourse etc.) and read through to see if there are certain words or phrases that you keep repeating. If there are, then try thinking up words you could use to replace them (use a thesaurus if you need to) and practice rephrasing your sentences. other than that, look at how you start each paragraph - its not a good idea to keep starting every paragraph with the same words (eg. to start successive paragraphs with 'However...' is very common), maybe you change some of these? hmmm...what else (sorry about the general terms but it is very difficult without knowing you/seeing your writing!) - if its a creative piece, maybe you could try to give your piece an interesting structure? off the top of my head, you could try:
-extended motif
-repetetition of key phrases in different context to emphasise change
-writing from the perspective of a minor character
-writing in 2nd person (as opposed to more common 1st and 3rd)
-varying short sentences and paragraphs
-starting sentences with hanging participles to add tension
hope it goes well dude!