The writing and publishing process is long and involved. I wrote the book, then had a friend who edits for a living proofread. After that I had the publisher do a proofread and I was amazed at the mistakes that were still found. It might be worth it to pay for proofreading.
If you plan on having paper books printed there are more expenses, minimum orders, etc.
I paid for proofing, cover design, and for the book to be made available in all of the e-book formats and listed with amazon, barnes and noble, etc. I also bought a quantity of printed books. It was somewhat expensive, but I am glad that I had the support while I published.