Check out airline fees for your planned flight. Preferably before you’ve booked it.
This is especially important with budget airlines. Ryanair has incredibly cheap flights. I’m not going to pretend otherwise. But they charge for everything. And I don’t mean just cokes and snacks. Seats, bags, snacks, everything you can think of that has to do with flying. If they could charge you for the recycled air, I’m sure they would. They also spend the entire flight pushing for you to buy whatever random thing they can find. Scratch offs, perfume, sandwiches. It’s absurd and annoying. Maybe it’s not so bad with noise-cancelling headphones…but I don’t own those. So I just have to put up with the annoyance if I fly with them.
That being said, some budget airlines offer the typical amenities of traditional airlines. Niki, Jet2 and easyjet are among my favorites. They still have low fares (admittedly, not quite as low as ryanair – but close enough for me) but they don’t try to hustle you.