You can snuggle down in a business- or first-class seat without paying a fortune

For me, flying in business or first class is not about the extra attention or the meals — which are still, let’s face it, airplane food — or even about the endless supply of booze (well, maybe a little bit).

It’s about comfort, especially on long-haul flights, when that lie-flat seat is crucial, but that comes at a cost. So I’m going to tell you how to fly flat without paying full freight.

Here’s how to fly business or first class for less (besides snagging a good fare when you see it).

Use miles/points to upgrade

American, Delta and United let passengers use miles (15,000 to 20,000) plus a co-pay of $75 on domestic routes in the Lower 48. Sometimes an upgrade is available immediately when you call the airline’s award desk, but usually you’ll be put on a wait list. How far in advance you book, the price of the economy fare and the time you check in for the flight may affect your chances.

Upgrades on flights to Hawaii and international destinations probably will cost more miles and come with higher co-pays. Other airlines besides those mentioned also allow mileage upgrades.

Use miles or points to buy

As with airfares, the number of miles or points you’ll need can vary. Check online first to see what you can find but don’t hesitate to call the awards desk. Last year I was looking for business-class award seats on British Airways and found none online, but an agent found lots of options. Check multiple times before committing.

Sign up for a credit card

Airlines are marketing credit cards aboard flights that offer added incentives not available online. On a recent American Airlines trip, the flight attendants handed out applications for a co-branded AA/Mastercard with no annual fee for the first year and a $1 minimum spend. I applied and used the miles for a free business-class trip.

Last-minute upgrades

Checking in online for an Alaska Airlines flight last year, I was offered a $50 upgrade to first class on a Seattle-to-Los Angeles flight. I took it.

Be alert for and ask about last-minute upgrades. Don’t ignore emailed upgrade offers: American frequently sends these, mostly on shorter domestic flights. TAP Air Portugal, which flies nonstop from L.A. to Lisbon, often sells upgrades to business class at the ticket counter or gate for about $400 to $500 per flight, depending on load factors.

Bid on an upgrade

Four dozen carriers (including Air New Zealand, Etihad, Fiji Airways, Hawaiian Airlines, Qantas, SAS and Singapore Airlines) offer upgrade auctions. Each has its own rules and procedures, so check your fare to see whether it is eligible. TAP Air Portugal runs auctions on Flytap.com from 72 to 24 hours before departure and at Seatboost.com from 24 hours to flight closing.

Dress well

I hear often from friends and readers that they have been upgraded to business or first class because they dressed decently. It happens only occasionally, but what do you have to lose? Several people I know have gotten Best Dressed Upgrades, most recently Susan Andrews, a real estate agent in L.A., on a flight to London on British, an airline on which she had zero status.

I worked for Eastern Airlines in the 1980s, and it was company policy to fly employees in first class if seats were available. One day I showed up for a flight in my best suit and good shoes but no necktie and was handed an economy class middle seat.

When I asked why, the gate agent said, “Dressed like that, you don’t deserve to fly at all!”