NEW YORK (MainStreet) — The rules keep changing. What you knew about airline rewards programs a few years ago, no longer holds true. An upshot: many hopeful flyers find themselves grievously disappointed when they try to cash in miles for trips. The other upshot: savvy travelers who play the game right are still taking dream trips. Here they share their secrets.

Case in point: recently this reporter flew nonstop from Phoenix to Newark airport (NYC) in coach, then a few days later flew first class from Newark to Dallas and again first class from Dallas back to Phoenix. The cost: 55,000 points and, yes, that’s a lot of Dividend Miles, but 40,000 came from simply signing up for a credit card and much of the rest came from mileage bonuses for buying air tickets with that card. And the stop in Dallas was desired, to sample the food at the American Express Centurion Lounge at DFW.

Rule 1: Travel during a down time for the destination. Other mileage trips in the past few years have been round trips from Newark to San Francisco, from Phoenix to Rome, from Newark to Paris. A big secret: the Paris and Rome flights were both in early December - a dead travel time. Airlines trip over themselves to fill seats then. Want a rewards ticket to Rome in July? Good luck with that (and why would you want to go anyway? Italy is expensive, overcrowded and hot in the summer). A starting point for succeeding is knowing to avoid peak travel times for rewards requests And book early. 90 days out is not too soon. Some experts advise booking six months in advance for highly sought routes (Hawaii, the Caribbean in winter, Orlando at Spring Break).

Rule 2: All airline miles programs are not created equal. Experts said they lately are avoiding United and Delta - which now calculate elite status not on miles flown but dollars paid. They also have upped redemption levels for free trips. That’s why Ryan Lile from the Frequent Flyer Academy said, “Know where the value is among the airline programs right now. Primarily that’s going to be American and Alaska’s programs in 2015.”

But don’t assume that will be true next year. Added Lile: “Be prepared to be flexible and follow value. While AA and Alaska have great programs this year, 2016 is an open question.”

A related fact: different airlines have different policies regarding how much reward travel they issue. Consumer Reports recently crunched Department of Transportation numbers and declared Southwest the most generous - giving away 11.5% of seats. JetBlue came in as stingiest, issuing just 4.5% of seats as awards. The others fell in the middle, said Consumer Reports.

Rule 3: “Earn and burn miles,” said Rocky Horan, a travel editor on Upgrd.com. He explained why: “Do not sit on a mound of miles, instead burn the miles as your earn them. If you have hundreds of thousands of miles sitting around, now is the time to use the miles before the airlines raise redemption rates again.” That is fact. Other airlines are believed to be enviously eyeing United and Delta and may make similar moves. You are not earning interest on that bank of 50,000 miles. Spend them, pronto.

Rule 4: “Double dip,” said advice columnist April Masini, who blogs at AskApril. She added: “Successful frequent flyers use a frequent flyer credit card, combined with the airline’s frequent flyer shopping portal — both of which allow consumers to double and triple dip in the mileage pool." For instance, buying an American Airlines ticket with an American Airlines credit card allows miles to be earned on the trip as well as the credit card purchase. The savviest flyers also use mileage award cards for routine purchases. Pay for a weekly Whole Foods basket with such a card and at year end that just may mean a free ticket.

A last test: Are you getting value for miles? The math is simple. Divide the ticket cost by the number of miles required to buy a ticket. A roundtrip from Newark to Paris is about $1,100 in early December. Say you pay 75,000 miles. That is a cost of 1.4 cents per mile and that - said the experts - is ready for takeoff. Two cents per mile is a homerun. But get more than a penny per mile in value and you have won. Get less and walk away from the deal. Use your miles for another, smarter flight later.

—Written by Robert McGarvey for MainStreet

This article is commentary by an independent contributor. At the time of publication, the author held TK positions in the stocks mentioned.