In so far as getting closing assignments, you need to sign up with either Notary Roatary or Gomobile notary or both. If you get a premiere membership you will get the calls.

With respect to problems with the closing documents, that is the title company's/lender's  problem. You do not prepare the closing packages. If there is a problem bring it to their attention for correction. If the correction necessitates rescheduling the closing, increase your price accordingly if it creates pressure on your pre existing schedule,. I had this happen last month, and I wound up getting $600 for the closing. Once you get comfortable with the closing business, the closings will become very easy.  I generally spend about 1 hour to 1 1/2 hours doing a closing. Occasionally there is a problem closing. I had one in September that ran 4 hours because the title company screwed up the closing package, but my price went up accordingly.