What are some verb-tense-mismatch errors commonly seen in an if statement?

I was wondering what were the most common errors native and non-native speakers made.

By tense-mismatch errors I mean something like:

"If I was born, I would been here."

Of course, it's not a good example, because no one would make such a mistake, but I am wondering what are all of the possible correct combinations in an if statement, and there's no schema that shows that in my knowledge.