Flying while pregnant

Natalie
Ladies who've flown while expecting, can you tell me a bit about your experiences? Good and bad, tips and tricks, would you or wouldn't you?
My husband and I have a long-haul holiday planned next year so our baby-making has yet to begin. I thought if we started TTC in March and were to get a BFP our first go, I'd be about 18-22 weeks during travel. 
I'd love to hear from those of you who've had experiences of flying in various stages of pregnancy so I know what I could be in for.