I haven't publish a book before so I can't say much, but some tips I would give you are :

1. Always have an outline based on the book you intend to write. Once you have a solid outline of it, do a number of drafts for each chapter (hypothetical) . Have friends or family members help you to scan the draft for errors and correct them.

2. Since you are writing a motivational book, please provide some sources to prove the point that you are trying to make. Cite plenty of resources and even use your own life experience as material for your book.

3. NEVER PLAGARISE!! Seriously, you shouldn't even publish a book if you plagarise. Cite all your resources from where they were and give credit to author of said books.

4. Never write the motivational book in a I-know-it-all way. Yes, you have plenty of experience but don't act high and mighty about it, since that would just put readers away.