What Kind of Changes Are Most Common in the New Testament?

What kinds of changes do we most commonly see in the New Testament? It's actually a fairly easy question to answer because there's kind of a limited number of things you could look for. Scholars typically differentiate between what are almost certainly just accidental slips of the pen, and what look like they're probably made intentionally. The earliest Christians making copies just happened to be the people who were literate in the congregation.