In a nutshell, travel hacking is working to accumulate miles, points or elite status to travel for free, or as cheaply as possible. Some people also focus on earning upgrades. There are loads of online sites dedicated to it, including ThePointsGuy and MillionMile­Secrets. I consider myself a travel hacking dabbler, but have found ample payoffs, including free airfare for four on a family ski trip, and sharply reduced hotel costs during our New York City trip.

As cash-back rewards continue to decline, sign-up bonuses can still be extremely lucrative, often netting 30,000 to 75,000 points per card. You can find some of the best deals at The PointsGuy's credit card page. If you'll be traveling with a spouse or partner, you both can apply for cards and earn two sets of miles. Ka-ching. If you have a business, that category of cards offers another opportunity for points.

For our trip to New York City, my husband and I applied for three new cards about six months in advance. We each applied for International Hotel Group (IHG) Rewards Club cards because we knew Holiday Inn Express would be a good option in New York City, with positive online reviews and free breakfast — a huge money-saver for a family of four. You need to apply that far in advance to allow time for cards to arrive, to meet spending limits, to pay off the bill, and for points to be awarded.

I found an offer that netted me 75,000 miles. Before my husband applied, that offer had expired and he got a card that awarded 60,000 miles (the same bonus available now). The annual fee is waived for the first year. In the end, we were able to use a combination of points and cash to book five nights (three with my points, two with his) at the Holiday Inn Express Madison Square Garden for $40 each night, cutting our hotel expenses by about 80 percent. Our IHG Platinum Elite status (earned with those free points) got us some treats at check-in, and, I suspect, the room we were assigned on the top floor of the hotel. I also had my husband apply for a Delta SkyMiles Amex card, which at the time offered $50 off your first Delta booking and a free checked bag.

The Delta card will likely be canceled, but the IHG cards have only a $49 annual fee and cardholders get one free night worldwide per year at eligible hotels. With college visits on our agenda next year, we're considering keeping the cards.

Here are some important caveats if you're considering travel hacking with credit cards. It's important to:

• Have impeccable credit: Many sites warn that credit card churn can adversely affect your credit rating, but I recently bought a car, and my credit remains excellent.

• Be willing to track purchases: Most cards that reward points have spending minimums (usually about $1,000) that need to be met and paid for before points are awarded. For cards that charge a fee after the first year, you'll have to weigh if and when to cancel.

• Have a plan: Don't just randomly apply for cards. You don't want points scattered among too many different reward programs. Have a specific goal and work toward that. Know which airline you hope to fly on and which hotel group would be the best fit.

• Consider cards that offer the ability to transfer points at a 1-1 ratio among different programs, such as Starwood Preferred and Chase Sapphire.

• Lifehacker has a good introductory guide for people who might want to dip their toes into travel hacking: http://strib.mn/1ubuznd.

COLLEEN KELLY