Ok, so you really don't need a 'how to' for this. Just gather the facts and write up what will help others. However, it appears we do need a 'how NOT to' guide.

The biggest problem I see is people that want a large count of reviews and guides, so they go copy and paste text from other reviews, guides, and other websites. Not only is this wrong, it is illegal.

If you have something that you have a lot of knowledge about, or feel strongly about, gather your facts and details and write it up using your own words. We can all appreciate people wanting to help us out, but the plagiarism should not be tolerated. If you see a review or guide that was copied from somewhere else, please click 'no' on the usefulness, then report it to whoever originally wrote the text that was plagiarized.