For me, flying in business or first class is not about the extra attentive service or the meals, or even about the endless supply of free booze (well, maybe a little).

It's about comfort, especially on long-haul flights. It's about being able to shift position, with the push of a button or two, from sitting upright to a much more comfortable lie-flat position. That's when my spine and posterior go "aaaah."

But airborne comfort comes at a cost. So I'll tell you how to fly flat for less than you might imagine.

1. Buy a nonrefundable business or first-class fare when it's low

Airfares change moment to moment and day to day. Search for a nonstop one-way in business class and the fare could be $499 one minute and $1,999 the next. I check multiple times as far in advance as possible and snag a deal when it appears. It's as easy as hitting the search button again and again to see if fares have changed. Often on domestic routes, nonrefundable business or first-class seats are just twice the cost of economy class rather than three or four times as much, as they once were. As with nonrefundable economy fares, you'll pay $200 to change or cancel.

2. Use miles or points to upgrade

Delta, American, United and others let passengers use miles (15,000 to 20,000) plus a co-pay of $75, on Lower 48 domestic routes, to upgrade from economy. Sometimes an upgrade is available immediately when you call the airline's award desk, but usually you'll be put on a waitlist. How far in advance you book, the price of the economy fare and the time you check in may affect your chances. Upgrades on flights to Hawaii and international destinations will cost more miles and higher co-pays.

3. Use miles or points to book

The number of miles or points needed to book a frequent-flier award seat will also vary day by day. I recommend calling the awards desk. Last year I was looking for business-class award seats on British Airways and found none online, but when I spoke to someone on the phone there were lots of options. That said, American was offering, on its app but not on its website, "online-only" business and first-class awards at greatly reduced mileage, so it's a good idea to try both methods. Check several times before committing.

If you have good credit but don't have enough miles in your account, the fastest way to earn enough for a business-class ticket is to get a new credit card offering sign-up bonuses after you charge a specified amount, usually around $3,000 in the first three months. (Delta's relaunched American Express cards currently offer 70,000 to 100,000 bonus miles.)

But do us all a favor and apply for these cards directly with the issuing bank and not through websites that get millions in referral commissions, since we consumers end up paying for these bounties in the form of higher interest rates and fees. To circumvent those "points" websites, airlines are marketing credit cards onboard flights with added incentives not available online.

4. Last-minute upgrade offers

Checking in online for an Alaska Airlines flight last year, I was offered a $50 upgrade to first class from Seattle to Los Angeles. You're darned right I took it. Waiting in line to board an Etihad Airways flight, I was approached by an agent who asked if I would like to upgrade from business to first class for $500. That one I didn't take, but you get the point: Be alert to, and ask about, last-minute upgrades. Do it when you check in at the airport. And don't ignore e-mailed upgrade offers: American sends me these all the time, mostly on shorter domestic flights. TAP Air Portugal sells upgrades to business class at the ticket counter or gate for about $400 to $500 per flight.

5. Buy through a consolidator

Consolidators are like the T.J. Maxx of business and first-class airfares. I've never used one, but my friend Ken did recently on a New York-to-London trip in business class for 50% less than Virgin Atlantic was asking online. One consolidator that's been in the business for decades is Planet Amex (planetamex­.com, no relation to American Express).

6. Bid through an auction

Four dozen carriers (Aer Lingus, Air Canada, Icelandair, Air New Zealand, Etihad, Hawaiian Airlines, Qantas, SAS and Singapore Airlines among them) offer upgrade auctions through PlusGrade.com. You must bid on each airline's site where you'll see rules and procedures, with some allowing upgrade bids on award tickets and some offering instant upgrades as well as auctions.

7. Be loyal to one airline

Although some airlines give away fewer free seats in business and first class than in the past, passengers with higher status in frequent-flier programs do get upgraded for free at times, and those folks also have higher priority on waiting lists for mileage upgrades.

8. Be nice, dress well

Time and again, I've heard from people who were upgraded simply because they made an effort to dress decently. It only happens occasionally, but what do you have to lose?

A British Airways employee confessed to me that, "Yes, we do take note of a passenger's behavior and whether they're presentable. When I was a check-in agent we would place a note in the comments section of the reservation: This person was very nice, consider available upgrade, or this person was very nasty."

Several people I know have gotten Best Dressed Upgrades. It's just human nature. Airline employees are required to dress smart when flying nonrevenue and they disdain passengers who dress like slobs. I worked for Eastern Air Lines in the 1980s when it was company policy to fly employees in first class if seats were available. One day I showed up in my best suit and good shoes, but no necktie, and was handed an economy-class boarding pass. When I asked why, the gate agent scoffed, "Dressed like that you don't deserve to fly at all!"