Airline miles let you book flights worth thousands, for pennies on the dollar. But, they're not always that easy to earn or redeem. Fortunately for you, there are plenty of ways to score more miles and maximize the ones you have, without jumping through too many hoops.

Co-branded airline credit cards offer one of the easiest ways to score a ton of miles in a hurry, thanks to their epic signup bonuses. Many airline cards offer 50,000 miles or more just for signing up and meeting a minimum spending requirement within three months. That's usually enough for at least two round-trip domestic flights.

Want to score even more easy signup bonuses? Consider pairing cards within the same program to double up on rewards. You could get both the Delta SkyMiles Gold and Delta SkyMiles Platinum cards, for example. Or, you could pair a Citi AAdvantage personal card and business credit card.

Another way to maximize your points and miles involves picking up a flexible travel credit card that lets you transfer points to more than one program. With the Chase Sapphire Preferred or Chase Sapphire Reserve, for example, you can transfer points 1:1 to airline partners like Southwest, United, British Airways and JetBlue.

Another way to maximize miles is by focusing on frequent flyer programs that let you earn rewards with different programs. With Air France/Flying Blue, for example, you can earn miles with the co-branded Air France credit card, Citi ThankYou credit cards, premier Chase travel cards and any card that earns points in the American Express Membership Rewards program.

Don't forget that you and your spouse can earn the same signup bonuses on the exact same airline and travel credit cards-even if you live at the same address. This strategy can help you double up on bonuses and earn twice as many miles in any given year.

With fare-based programs like Southwest Rapid Rewards, you can fork over fewer miles for the flights when they go on sale. When it comes to programs with fare-based awards, make sure to keep your eye out for special deals and pricing so you can stretch your miles as far as they can go.

Also keep in mind that flights with certain frequent flyer programs can cost less if you fly early, fly late or choose flights with several layovers. This is true with fare-based programs like Southwest as well as frequent flyer programs like Delta SkyMiles that don't post an award chart.

Some airline programs like American AAdvantage offer cheaper rates for off-peak awards. For example, one of American's best deals is their off-peak flights from the U.S. to Europe from November through April. These flights cost 45,000 miles round-trip instead of the 60,000 miles you'll pay the rest of the year.

Another important part of maximizing your miles is knowing when not to use them. Most experts say you should never redeem airline miles for less than one cent each. If that's all the value you're receiving, you should pay cash and save your miles for another trip.

Airline shopping portals from airlines like American, Delta and United let you earn additional miles when you make purchases at participating stores online. If you're going to shop online anyway, there's no reason not to click through a portal and earn more miles for each dollar you spend.

If your favorite airline is part of an alliance, make sure to check award pricing on partner airlines before you book. A lot of the time, partner airlines can get you on the same flight for fewer miles or a better deal when it comes to those dreaded fuel surcharges.

Award booking agency Juicy Miles has its own award searching tool that lets you search for award seats across multiple airlines in place. A five-day unlimited search pass costs just $9.99, yet it can help you get thousands of dollars more out of your miles with the right redemption.

Travel credit cards like the Platinum Card from American Express offer airline reimbursement credits that can cover checked baggage fees, online internet access and other travel incidentals. If you let your travel credits go to waste, you're leaving free money on the table.

The Delta SkyMiles program lets you earn 1 mile for every dollar you spend on rideshares with Lyft. You can also earn 2x miles for rides to and from the airport. Fortunately, connecting your Delta SkyMiles sand Lyft accounts is free and easy to do online.

If you're having trouble finding award seats on flights you want from your home airport, don't forget to check out airports nearby. You may find the bigger airports have more award space on a broader range of dates and flights could even cost fewer miles with some programs.

Some airlines offer a companion pass that lets a companion fly free or at a reduced fare. The most popular companion pass comes from Southwest Airlines. Their Companion Pass lets a friend or family member of your choosing fly free for the year you earn it and the entire following year whether you pay for your flight in cash or points.

Don't forget that you don't have to fly into and out of the same airport. Not only can booking an open jaw flight that departs from a second destination help you preserve airline miles if prices are lower, but it can also help you avoid backtracking to your original destination.