And I can't believe I'm doing this one. Maybe it's because my 2nd and 3rd grade teachers pounded this into our heads that I find this error such a surprise, but here it is.
To--Too--Two
To--a preposition. The start of a prepositional phrase. (Ex: I am going to the store.)
Too--an adverb. Too = Also. But it can mean more than enough or extremely.
(ex: I want to go, too.) or (ex: The water is too hot.)
Two--is the number 2.
I just very recently saw to and too mixed up and used incorrectly. I stress that this is not to criticize. It's to help. Little things like these mistakes are what make Indie Authors unpopular with the readers, the publishers, and the agents. I wish every author success.