Revision is a crucial step in self publishing. Do not assume that your work is perfect. It isn't.
I revised the crap out my novel, but I didn't do as much as I should have.
I recommend AT LEAST EIGHT revision passes, probably more would be better. Each time you will look for errors, typos, and mistakes, cut out things that aren't working, add in better descriptions, remove passive voice and overuse of adverbs, and slash any cliches you find.
You need to revise until you don't want to read another word, until you are sick of your novel, hate it, want it dead. Your eyes will bleed with hours of staring at the computer screen or pages you printed out to mark up.
Are you done at this point? NO!!
Then you need to give it to someone you trust, someone who will be somewhat brutal with you and have them go through it a couple times. This also gives you a break from the manuscript so you can come back to it a few weeks later and go through it several more times.
You will reach a point where you want to take your book out back and set it on fire and then dance on the ashes, screaming at the gray sky in despair and agony. That is when you are close to done.
You should set it aside and wait a few more weeks before doing one final revision to the entire book.
Maybe people's expectations are skewed when it comes to books. They expect perfection, demand it, more than it seems any other industry.
I had a podcast review after I had fixed many typos that readers had found and I thought the book was close to perfect. The reviewers talked about how they loved the rich world I'd created, complete with mythology and back histories. They loved that every character felt unique and different as I hopped in and out of a dozen character's heads. They loved the story. Then they had to mention that it had an "unusually high amount of homophone mistakes." They went on to list them, totalling two. TWO!!
My jaw fell open as I listened. Seriously? Two?
In any other industry with that kind of mistake average, I'd be freaking Employee of the Month!
So, the point of all this ranting is REVISIONS ARE IMPORTANT. Do them, do them until you bleed! You will thank me.