Forget colouring books and pencils etc - you'll have too much to carry. My most honest tip would be pay for a parent to fly over and then fly back with you, both directions.
If that's not possible, the tricky bits are going through security (takes ages to get children out of buggies, shoes off, bags (esp milk) checked etc), divesting yourself of pushchair getting on the plane (as you then have to carry bags and children onto plane), and then collecting checked luggage at the end, as it's impossible to push a luggage trolley and a pushchair (I had to push the trolley a few feet, then push the pushchair a few feet, then go back for the trolley and so on, until a woman took pity on me and helped). I found airline staff not very helpful in this regard - perhaps health and safety means they've been told not to carry babies? Think about how you'll do these things with just you.
If you can, book enough plane seats so you can take up a whole row, ideally with a spare seat you can put the baby on so you can get stuff out of your bag (otherwise it's impossible to get stuff out of a bag at your feet without crushing the baby on your lap). Be prepared to ask for help from fellow passengers!
Don't drink much in the way of fluids yourself as going to the loo is tricky...
Accept it will be awful, don't rush yourself and don't stress - you will do it, you'll never do it again, but it will be ok.