It is best if you can complete your ISO documents on the computer and print them off, but this may not be possible in all cases. If you must fill them out by hand, that's ok, but make sure your handwriting is neat! It is best to use blue pen so that your original copies can be easily identified.
Include as much of the information being asked for as you can. Remember, if you need more room than what's provided on a document, you can attach a blank page to the back of the document to continue writing. Be sure to note on the extra page which document it belongs with, in case the extra page becomes detached. If you have a lot of extra information to give, it may be best to do so by writing an affidavit.
It is always a good idea to speak with a lawyer for advice, and to have them review your completed documents whenever possible.