Say you want to start a permaculture project, and you want to do it right from the beginning - where would you find specific advice, as to:
How large need your swales to be?
How much horse manure do your plants need / tolerate?
Is your readily available wood ok for hugel beds?
Where and how to plant trees?
What plant associations make sense in your climate zone?
Right here on Permies, is one place, you can search the wiki pages.
Your local library is another great place, look for books on building the soil, water management methods, etc.
A third option is a book store, where you can find the books by the authors that are leaders in their field.