Definitely skip MiB International if you loved the first one, you will only be disappointed with this one. I would venture to say the franchise should end for fans at the first one. The next tree just don't hold a candle to it. This is not an Indiana Jones movie franchise, up to the third, situation.

I would suggest picking up a trade paperback of the comics, if one is available, instead of watching the sequels. Maybe watch the cartoon series and act as if the three sequels don't exist because as they came out, they have steadily hurt the franchise.

I liked International more than 2 and 3 because you get to see more of the overall universe. You don't learn anything new about the previous movies though so there is not even that for fans of the first to be tied to this one.