The only thing worse than waiting in a security line or a crowded airport terminal is squeezing into a narrow coach seat. Seat 32B, to be exact. As you enter the plane and prepare yourself for the next four hours of misery, you'll probably pass some happier passengers sipping on pre-departure beverages and sprawling across their roomy first-class seats.So why aren't you joining them? Upgrades do cost something, whether that payment comes in the form of money, frequent flier miles or elite status. But you probably already have what it takes to sit up front or can find a way to make the jump more affordable.See: Best Airline Rewards Programs of 2014-2015Most first-class upgrades are given to elite frequent fliers who receive them as complimentary benefits on domestic routes. Although paid and award upgrades have priority, there often aren't enough to fill all the empty seats on a given flight. The trick to getting upgraded is thus two-fold: seek status and choose the right flights.Consolidate your travel onto one carrier or alliance rather than distributing it among several airlines. If it costs a bit more, compare the price to what you might save in other benefits like upgrades, priority seat assignments and waived fees. But if you plan to fly with an affiliated airline, remember that complimentary upgrades generally only go to members who have elite status with the operating carrier. American Airlines, for instance, would rather upgrade a member of its AAdvantage program before considering anyone from the Cathay Pacific Marco Polo Club.Choosing your flights wisely is more complicated but simple enough in theory: Fly when no one else wants to fly. Consider leaving on a Saturday morning after everyone's returned home from their business trips or left for the weekend. Taking connections helps, too. No one likes to go out of their way, and these routes have more price-sensitive and typically less frequent travelers. As an added bonus, you might save money when compared to nonstop routes favored by road warriors traveling on the company's dime.Your best bet is researching each carrier's unique rules governing its upgrade policy. American gives priority to connecting passengers, for example, and considers the time of the upgrade request (often when the flight was booked). United Airlines, on the other hand, penalizes a couple traveling together because there must be upgrade space for both or else the system skips over to the next single passenger. United’s upgrade policy also ranks passengers by the fare paid; sometimes spending $10 more for a higher cabin class can increase your position in the upgrade queue.See: Delta and United Put a Price on Loyalty — Should You Pay It?In the days leading up to departure, upgrade inventory doesn't typically match the number of first-class seats available because airlines aim to sell them at full price. But carriers can still track the numbers closely. For airlines faced with a choice between giving a seat away for free or collecting some extra cash, money takes priority over rewarding loyal customers.Upgrades can often be purchased at a discount compared to the regular cost of a first-class ticket. Some carriers offer this option at check-in or when you view your itinerary online, while others may have a fixed price or auction system at the gate. Keep in mind rules vary greatly between carriers. And unlike the treatment you would receive if you purchased a first-class ticket, you'll be treated according to the rules of the original fare. That means fewer frequent flier miles and higher fees for schedule changes.But there are also some fares that are sold as economy class tickets that include an automatic upgrade to first class. Often called "Y-UP" fares, they'e not exactly cheap. They just happen to be less expensive than paying for first class outright. Elite frequent fliers may be offered similar instant upgrades when they book full-fare tickets even if they aren't advertised with the Y-UP name.Carriers will let you pay for a regular ticket and upgrade it later using frequent flier miles. However, many upgrades still require a co-pay, especially for the cheapest discount fares. United charges as much as 20,000 miles plus $550 each way for a business-class upgrade between North America and Europe. If you want to upgrade a partner flight (e.g., using United's miles on Lufthansa), the co-pay requirement is dropped, though you will need to buy a full-fare ticket. Calculate how much money you will actually save for a discounted business-class seat before redeeming an award upgrade with both miles and a co-pay.It probably comes as no surprise that upgrades are generally a bad use of miles. Continuing with United as an example, an upgrade within the U.S. is 20,000 miles plus $75 for a one-way flight. You could redeem a first-class saver award for just 25,000 miles. But some people never save enough for a free flight, can't find award space or just don’t want to travel more than they're already obligated to. Using miles in any way is better than letting them expire.See: Are Frequent Flier Programs a Fool's Game?Passengers with no extra money, no miles and no elite status will probably only enjoy a first-class experience thanks to operational upgrades (i.e., upgrades given at the discretion of the gate agent).Is your flight's economy class cabin oversold? Someone has to move up to first class. Or conversely, a passenger may be willing to take a later flight, with a seat in first class as compensation for the inconvenience. Never settle for the agent's original offer, as there are many little things he or she can do in addition to doling out cash. Other issues like a disruptive passenger or an inoperative television screen might provide justification for reshuffling passengers on-board.Stories about a well-dressed customer who asks for an upgrade are the exception rather than the rule. More important than how someone looks is that a seat is available, the passenger is friendly and the agent has a problem that needs to be resolved quickly. These upgrades are all about the luck of the draw. Rather than buying a new suit, consider trying out the other options listed above.About the author: Scott Mackenzie is a neuroscientist who learned how to travel and earn elite status on the cheap during graduate school. He now shares these tricks on the blog Travel Codex. You can also follow him on Twitter @Travel_Codex.