Are you flexible on your dates at all? That's honestly the biggest money-saver. Ryanair and Easyjet are still pretty cheap if you book far enough in advance and watch out for their sneaky fees, though you'll want to factor in baggage costs. Wizz Air tends to have some solid deals too, especially if you're heading to Eastern Europe. Most people I know are mixing budget carriers with maybe one or two slightly pricier flights to avoid getting stuck somewhere, and they're doing okay with their budgets that way.