Never use blue ink in a pen ALWAYS use black ink. I was reading somewhere once and it said by using black ink in your writing it makes employers think its more professional whick increases your chances of getting a job.
If it's a handwritten form keep it neat, made a couple of copies of all pages so if you do mess it up, you have a spare. It also allows you to make sure everything you want to say will fit in, especially if you have to write a personal statement.
Keep everything concise and don't waffle. If you haven't written enough to fill a section, then don't worry about it.