article: He made the headlines for his plan to travel 20,000 miles on 21 flights in first class... without paying a penny. Now American 28-year-old Scott Keyes has revealed his savvy secrets so you too can explore the world without falling into the ticket traps. The Think Progress reporter reveals his travel hacks in his eBooks How To Fly For Free and How To Find Cheap Flights, and spoke to MailOnline Travel about his top tips. Scroll down for video . Scott Keyes (above), a 28-year-old writer for Think Progress, is about to travel 20,000miles on 21 flights . Globe-trotter: Along the way he will be stopping by 13 countries in Europe and South and North America . Stock up flyer miles through credit cards . Keyes recommends credit cards are the best way to go if you want to quickly and easily rack up frequent flyer miles, which you can then use to take free flights. He only sign up for cards with high sign-up bonuses and relatively low spending thresholds necessary to get those. For example, a card he just got gave 50,000 bonus points for spending $1,000 in three months. The writer makes a point of putting all everyday spending on credit cards in order to hit these spending thresholds. (Unfortunately, this is mostly true for American travellers; European credit cards and elsewhere tend to offer fairly meagre perks.) As long as you can handle credit responsibly and treat your credit card like a debit card, you can work towards a surprising amount of free travel. My favourite credit card is almost always whichever one offers the best sign-up bonus at the time. So right now, the best three are American Airlines' Citi Platinum card, the United MileagePlus Explorer card, and British Airways Visa Signature card, each of which offers a sign-up bonus of 50,000 miles. (For complicated reasons, I probably like the BA card the best, because if you're flying less than 650 miles, 50,000 miles will get you as many as 11 free flights.) I basically ignore the 'get one mile for every dollar you spend' incentive, since I don't have much money to spend. In order to get as many miles as the sign-up bonus, I would have to spend $50,000! I focus almost exclusively on the sign-up bonus when deciding what card to get next. Keyes uses a number of techniques to travel first class around the world for free, which he has revealed in his two eBooks. Here pictured in Mexico . Fly on the cheapest days of the week . Be flexible with your dates when you want to take a trip of a set number of days. Often times a Friday-Monday flight will be cheaper than a Thursday-Sunday, for instance, even though it's the same number of days. Usually the cheapest days to fly are Tuesday, Wednesday, and Saturday. Keyes poses while rafting down Sumidero Canyon which is located near the city of Chiapa de Corzo in Mexico . Check the day before and after for cheaper fares . Always search one day before or after just out of curiosity, because sometime red-eye flights can technically leave on the next day. These flights leave late at night, arriving in early morning and inside the US these flights are almost exclusively for travel from the West to the East. 'I once helped my friend George cut the price of a round trip flight to Vegas nearly in half by finding a redeye flight that left just after midnight, making it technically a Monday flight and not a Sunday flight,' Keyes tells MailOnline Travel. Wading into the waters of Hierve el agua in Oaxaca, Mexico, rock formations and the remnants of old geysers . Work backwards with your trip . If you want the cheapest flights, chase the fare, not the destination. In other words, rather than picking a destination and then looking for the cheapest way to get there, start out by looking where there are cheap flights, and then decide among those where you'd like to go. Keyes explains: 'I never had my heart set on going to Milan, but when a $65 flight from NYC-Milan popped up, I jumped on it. 'That's too great a deal to pass up, after all.' The 28-year-old having fun wearing a tortoise shell in the Galapagos Islands on holiday . Search for the whole month for flights . Refer to websites such as Kayak and ITA Matrix which give you an month's overview of flights a prices. Make your itinerary as flexible as possible so you are able to opt for going a few weeks after you intended to get the lower fares. Enjoying the view! The writer recommends flying on a Tuesday, Wednesday, and Saturday as these are usually cheaper . Try flying to gateway airports . If you're flying to a different continent and want the cheapest price, you should search for a number of different gateway airports in that region. For example, if you want to fly to Bali, start by searching for flights to Bali, but don't stop there. Also look at the cost of flights to Jakarta, Bangkok, Hong Kong, Singapore, and Kuala Lumpur. If any of those flights is significantly cheaper, you can usually find a cheap budget flight from there to continue on to Bali. Searching leg-by-leg like this can save hundreds on your overall flight cost because flight search engines usually can't combine a long haul flight on one airline with a short flight on a separate budget airline. Ocean views in the Dominican Republic. The flyer picks the flight before choosing a destination to visit, to save money . Dayton, Ohio - Dallas, Fort Worth - 861 miles . Dallas, Forth Worth - Mexico City - 935 miles . Oaxaca, Mexico - Mexico City - 228 miles . Mexico City - Managua, Nicaragua - 994 miles . Managua - Panama City - 507 miles . Panama City - Port of Spain, Trinidad - 1234 miles . Port of Spain - St Lucia 217 miles . St Lucia - St George's, Grenada - 131 miles . St George's - Miami - 1535 miles . Miami - Dusseldorf, Germany, 4733 miles . Dusseldorf - Dresden, Germany, 304 miles . Prague, Czech Rep - Vienna, Austria, 173 miles . Vienna - Kiev, Ukraine, 665 miles . Lvov, Ukraine - Vienna, 356 miles . Vienna - Sofia, Bulgaria, 500 miles . Sofia - Vienna, 500 miles . Vienna - Vilnius, Lithuania, 587 miles . Vilnius - Helsinki, Finland, 393 miles . Helsinki - Berlin, Germany, 697 miles . Berlin - Chicago, 4412 miles . Chicago - Dayton, 240 miles . Total: 20205 miles . Don't book in advance . Don't buy domestic flights more than one-three months in advance. Fares rarely go on sale further than three months in advance, so you'll miss out on some upcoming deals if you book too early. On the other side, don't wait until the last minute to book. Unlike 20 years ago, standby fares are mostly a thing of the past and fares tend to shoot up in the final days before a flight actually takes place. For popular flight times during the holiday season or for long haul, look six months in advance. Being bumped is not the end of the world . Being delayed or bumped from a flight is a situation many travellers fear. However it could prove to be in your favour with some airports if you ask for money or frequent flyer miles instead of flight vouchers. 'I was once given a $500 voucher and a confirmed seat on the next flight — an hour and a half later,' Keyes wrote in How To Fly For Free. 'In other words, I earned $333/hour. 'Like me, if your goal is to fly for free, you probably don’t make $333/hour. 'Plus, unlike flights you book using miles, you actually earn miles when you pay using a voucher.' Keyes is seen posing in front of the famed Materhorn on a previous trip, which straddles the border of Switzerland and Italy . Take advantage of tweet deck and email alerts . Don't make flight hunting something you only do when looking to plan your trip. Constantly be updated with alerts and tweets promoting the cheapest tickets. Keyes recommends the best newsletter alerts are from Airfarewatchdog and The Flight Deal. You can also sign up to receive emails from the savvy traveller himself for deals he comes across. The writer recommends being open to stop off at a gateway airport in a cheaper destination, before continuing with the second leg of your journey to where you want to go .
highlights: Scott Keyes, 28, has cracked the system around the world for free .
  The writer reveals his secrets in two eBooks and to MailOnline Travel .
  Tips include savvy use of credit cards, knowing when to book, and planning the destination after selecting the flights on offer .
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