If you are a frequent traveler, then you probably get miles already just by flying. However, you can earn frequent flyer miles without boarding a plane every month and even without leaving house at all. The bottom line to mile earning is to spend, but in a smart way.
First things first, you need to sign up for frequent flyer programs on all airlines that you use. It’s best not to spread around, but to aim at specific ones: that way you won’t end up having low miles balances all over, but accrue a decent number of miles where you might actually spend them. For example, if Avianca never flies through your local airport, it’s not that useful for you. After that, just proceed to traveling, miles will add up automatically. Bear in mind that miles amount the number of miles you’ve flown, not the number you are about to. Thus, if you had a 50000 miles flight, that will be roughly equal to $500 in traveling. Most airlines have an approximately mile =1 cent rate.
The next thing to do is to sign up for travel credit cards. Credit cards give you sign-up bonuses that can be massive and miles on various purchases up to 5 miles a dollar. My advice is to get as many as you can manage. Credit cards themselves won’t get you into debt, and having more than one will do good to your credit score, provided that you don’t max them out and, most importantly, pay your balance off each month before the due date. Miles are given for spending, so transfer your major payments to credit cards. Get some cards with sign-up bonuses like Barclaycard Arrival Plus® World Elite Mastercard® or JetBlue Plus Card and pay your taxes or make big purchases like a TV during the first period of using to qualify for a bonus, since such cards tend to require $1000 to $3000 spent in the first months. If you are reluctant to pay annual fee, get Discover it® Miles and have your miles doubled at the end of the year.
Credit cards give you double or triple miles for some positions, which are mostly accommodation, car rentals and some of them even for groceries (just imagine 3 points per dollar just for your everyday food shopping!). Check that out and plan your spendings strategically. Besides, there are lucrative deals that come and go, such as testing things or buying wine. Those you need to follow, which is best to do at travel-oriented sites. Finally, you can earn miles without spending a penny! Just fill out a couple of online surveys on sites that offer rewards for it and earn 100-1000 for a survey (it takes up to 20 minutes, but you can choose small ones that take no more than 5 minutes).
Overall, it might seem confusing, but earning miles is not actually that difficult. Investing some time and channeling your purchases may lead you to virtually free flights.