The cover sets the tone and stage for what's inside. Also, no clip art or some other generic graphics. AI is cool, but not a substitue or a crutch. Be original. I also use my own photos.
If it drains you that's part of the process. If it stresses you out, step back and wait. And when you think your ready. Wait 15 minutes and then start again. If you're still stressed come back the next day.