The biggest tip I can say is to take your time. If you rush through writing a book, it only leaves you with more work and there's even a chance that it'll be... well not your best. So, here is the process that I've heard several times within the past week when I asked other authors for their advice.
2. Find a critique partner
3. Fix critiques suggestions
4. Do a personal edit on your work
5. Find a professional editor.
6. Fix the suggestions from the editor.
7. Send to beta readers.
8. Fix beta suggestions.
9. Send back to the professional editor.
10. Fix last edits
There's a lot of work that goes into self publishing, which seems to be the hit right now. Authors take anywhere from months to years writing their books. The writing aspect isn't the only thing that is done to a book before readers get them in their hands.
For those of you looking for help with writing your book, I suggest you check out The Bookshelf Muse's blog. There's a lot of information here for descriptions. I love it and they also have an ebook and paperback available.