It'll take a while to write a very good guide. I'm a guide-writer myself. So here are some tips:
1. A good guide must be easy to understand. It has to be "noob-proof"
2. Pictures aren't always necessary, but as they say, "A picture says 1000 words"
3. Make sure you set an example with good English Grammar. A good guide is easy to read.
4. Add some humor every now and then. The topic your writing about is a long one, so it'll be hard to keep the attention of the readers, so this is a must.
Good luck with this, I support
~Z