Just follow the instructions (link)
by ndtnguy (2019-01-11 14:39:59)

In reply to: Easiest way to file for a 501c3?  posted by mintirish

The form is a bear, but it's not rocket science. Unless your activity or entity structure is weird, it's really just a matter of making sure your formation structure uses the proper magic language and checking off the boxes.

If you're a school, or something school-related, it becomes a major headache and you need to read a bunch of revenue rulings. But otherwise, I would just take a look at the instructions.