How do you get cheap flight tickets if you're a constant traveler?

Try Expedia.co.uk

or another option is using low-budget airlines like EasyJet, WizzAir, RyanAir, etc

Or by the use of American Express - purchasing tickets by Amex gives you points and AirMiles then you can use to reduce the price of your next booking.

Hi! By focusing on cost-effective passengers, Frontier Airlines differentiated itself in the market by attracting a loyal customer base. Its low-cost approach allows many people to travel more often without spending a lot of money. It is worth saying that despite the low prices, the quality of their services is high, and at the same time, frontier airlines customer service tries to do everything possible to ensure that each of their passengers gets the best experience from using the company’s services.

My first choice every time is Qatar Airways because it is one of the best travel portals that have been giving great services as well as offering special discounts on flight bookings. I always first check for Qatar Airways promo codes then go for anything and i am sure that who wants to travel to different destinations worldwide definitely love getting 50% off on bookings and that is where i would find the special discount on bookings. 

You can also check the Qatar Airways coupons, offers & promo codes that save a big amount on bookings every time.

there are several ways to get tickets with lower cost, for examble:

1-you have to arrange your trip as earler as possipole to get the chance to book the lower classes or the promo classes.

2-create frequent flyer membershep on the most useable airline for you to get the benefit from the miles program such as free tickets against miles or upgrad to business class with miles. 

3- try to target the low season period to get the special rate. 

4- if you are traveling for business and own a company and have a lot of staff and co workers who travel too, you can create a spcial deal with your most useabl airline.