Contracting services to third parties, cheap 2nd hand planes (to start off with), no landing fees (airports even pay FR to land), food & duty-free sold at above-average cost, all sorts of expensive fees to make changes, where changes can't be made, pax are asked to purchase a new ticket at full-fare (still cheaper than BA etc.), credit-card fees, telephone numbers available, but at premium rates (50p/minute), credit card "handling fee" if you book with Visa etc., more fees if you book by phone, tickets are electronic (money saved as opposed to issuing paper tickets),
only a limited number of seats per aircraft sold at bargain prices; fares increase rapidly once those seats are sold.
Multi-skilled staff (check-in agents, gate agents all the same), cabin crew also clean the a/c and all staff have to pay a flat fee of £25 for a RT on any FR flight.
And those are some of the "tricks" that these no-frills airlines employ to make money; my hat off to them for allowing even students to jump on the plane at the weekend
Oh, and by the by, it's StanSTED not STEAD. Cheers & happy flying.