Proofread. Proofread, proofread, proofread. If you don’t, you look like a dumbass.
I allowed myself to upload a cover image with two typos. Thank the Gods that the only copy ordered was purchased by a coworker and that she wanted me to autograph it for her! (I plan on purchasing a good copy for her as a gift, so she doesn’t have to have a “bad” printing as her only copy.) She didn’t mind, but I feel bad that she got that copy, even though she seemed to truly like it.
Watch your product, fellow writers. You have to be involved in every step of the process, even if you don’t do it yourself or don’t understand that step. Make sure you approve everything and all the T’s are crossed and I’s dotted. Unless it’s a capital I. Because those don’t get dots.