Well, how about I give two: one for the craft and one for marketing?
When it comes to writing, trust your instinct. If it feels off, it is. Sit and wait, go for a walk, take a shower, or skip it and come back to it, but DO NOT force it if it just doesn't feel like it's working. If you think something is wrong with your story, I guarantee you, others will, too.
As for marketing, keep your expectations reasonable. Tell yourself that no one may read this book. They may hate it. You may only sell 5 copies. If I hadn't made Bully free or $.99 nearly the entire time it was self-published, it may never have seen the light of day. I didn't expect to make money, my expectations were low, and I was wonderfully surprised.
I hope that helps in some way. Like I've said, I've been luckier than most, and it can be very hard for others. <3 Good luck and stay true to yourself.