Plane ride with..

Hi in June I will be going on a trip with my fiance and my son who will be 8 months old when we go.

We have one stop going to our destination and one stop on the flight home as well.

The longest time on our way home will be 4 hour flight,, the other 3 planes will be 3 or less hour flights.

What are some must haves to bring?

Any tips on traveling with an infant? Things I need to know?

Let me know, I wanna be prepared :)