The book Andy recommended by NOLO Press should be very helpful.
Sandy Deja, EA has created an excellent resource to walk you
through the process of filling out the IRS Form 1023 package.
She tells you how to do it. When not to do it.
There's a page by page guide to help you fill out the forms.
Did I mention that it's free?
Once you've filled out all the information on the IRS Form 1023
(which is a booklet, really), you'll need to use that information
to fill out the California application, too. That is Form 3500,
also a booklet.
You'll find more information about California's requirements here:
Incidentally, let me save you a little bit of money.
Don't file the forms to become a California corporation.
It's part of the Form 3500 set-up and will save you all the
But, yes, before you do anything, read the information on Sandy's
site. It will help you understand the pros and cons of operating
a non-profit entity.
IRS also set up an excellent resource about Charities you might like:
it also helps you through the thinking process, step-by-step.
One thing you'll need to understand before you embark on these
applications - they require that you have a business plan and
a budget, and some idea of what your written material (brochures,
ads, etc.) will say.
Incidentally, if you want to see live examples of charities'
articles, by-laws and tax returns, find a charity you like
here - and see their public filings:
[Search strategy, I used the links I've built up over the years
within my own resource base.]