Authors have three chances to make a good impression; the cover, the title, and the blurb. All three had better be good or the potential reader will move on to something more interesting. Don't cheap out on a quality cover; use a talented graphic designer who has experience doing book covers.
Don't let yourself get stressed. Write when you can and what you can. If I'm stuck and starting to feel stressed, I leave that chapter and write a scene from later in the book. I often have half a dozen chapters written out of sequence that I weave back in.
