Take the time to edit with all five senses.
Sight:
You want to write a beautiful book. Anything less just is not fair to any trees that might die for your printed work.
When print books were all you could get (many moons ago,) a writer fortunate enough to get published by a book company of any significance would have their work packaged by professional editors and designers. The result was a clean text proofread to the letter, intelligently selected fonts, and an artistic jacket that made buyers want to display the book like a status symbol.
Now, sales to younger buyers are via e-book, and you can thank the anonymity of the e-reader gateway for not personally associating you with the boring or silly padded covers that are sold for the devices. I am pleased to have an iPad (it saves certain natural resources), but I have yet to find a cover that is worthy of it.
For first time print book self-publishers (at whom I am aiming these three posts), the first order of business is making sure you have no obvious typos. Nothing takes away the smooth experience of drinking in a book as do careless visual errors left in. And unlike in a blog, you cannot go back and fix the mistake after it is published. Have at least one patient and careful reader friend scan your book or preliminary copy (galley) after you have spell-checked it electronically.
Assuming that you have any choice at all in what the cover and typesetting will look like, ask a genuinely talented artistic friend to give you some input, and see if you agree with their assessment. A high quality self-help book deserves to be eye-catching, and a well-chosen cover may earn it a place on the office bookshelf of some influential book collector. Self-published books often have a bland cover that reminds me of the little booklets at the supermarket check-out. They have a did-it-myself look that signals an unworthy read, whether that's really the case or not.
Next up: How does your book sound?