For the cheapest but not always cheerful flights, head to Easyjet and/or Ryanair websites. The cost of a flight can sometimes determine my destination.
Flights to cities such as Barcelona, Budapest, Nice, Milan and Amsterdam can be as cheap as £10 out of high season with budget airlines.
But be-warned, travel bag allowance rules change constantly, make sure you're up to date on the policy, because you could end up paying double than the initial cost of flights.
I wouldn't bother with seat allocation if you can avoid the extra cost, everyone ends up swapping seats to sit with their friends & family usually!
Long Haul Flights
For long-haul international flights I often use Skyscanner. If the travel agent has poor reviews and/or not many legitimate reviews, I am cautious and tend to not use that agent. However, reviews can’t always be trusted. Agents such as Travel Up have mixed reviews on TripAdvisor, but I have used them on numerous occasions and have had zero troubles. The key is to make sure they're ATOL and/or ABTA protected.
Long-haul flights can often range by hundreds of pounds just by changing the day of outward travel.
During the week tends to be cheaper than flying on weekends, but this isn’t always the case, so play around with the dates if you’re flexible.
Always book a return flight (if you want to come back..). It is often cheaper to book return flights than it is for two separate single journeys.
Prepare yourself, for the low-cost flights, it's likely you'll be setting the alarm for an ungodly hour.
For people who fear stop-overs ... you'll be fine. It often feels rushed because you don't want to be stranded in an airport, but if you have 2 hours in Dubai airport, you'll probably find yourself getting a bit bored and overspending on snacks. Just remember, you will have to go through security for your connecting flight.And yes, your bag will be transferred onto the next plane by the airline staff.
If it's a layover and you're spending the night at the airport, you will need to reclaim your luggage and check in the next day for your final flight.