In July, travel-points expert Brian Kelly posted a surprising announcement on his website, the Points Guy (thepointsguy.com). United Airlines was running a business-class-fare special from New York to Hong Kong for just four frequent flier miles and $43 each way. Sounds unbelievable, right?

Kelly was certain the fare was a mistake, what travel experts call an “error fare,” but he told his thousands of readers and Twitter followers about the deal. Many booked the flight before United noticed the error. The airline refused to honor most tickets, but travelers who left for Hong Kong within five days of booking got the round-trip flight — normally about $10,000 — for a few points and less than $100.

“That fare was really unique,” Kelly says. “The mistakes usually happen with paid tickets, when an airline will forget to add taxes or an extra digit to the price,” Kelly says, adding that it’s unusual to have a mistake apply to all flights on one route.

The thrill of error fares and amazing deals is an added incentive for people to rack up miles and book trips strategically. Kelly says that more than ever, credit-card travel-rewards clubs are trying to attract new customers with sweet bonuses.

We talked with Kelly to learn his tips and tricks for racking up 125,000 miles a year (without flying!). Trust us, even experienced travelers will be impressed by how experts get the most out of their bonus points.

HOW TO GET MILES

• Get in on the credit card game: If you want to rack up miles quickly, you have to be in on the credit card game. “It’s so lucrative for the companies,” Kelly says. “The credit card companies were shedding customers during the recession. Now that economy is getting better, they’re looking to get back creditworthy consumers.” But Kelly doesn’t recommend that people in debt get into the game. It’s only for people who pay off balances every month.

• How many accounts should you open: It’s free to open up miles and points accounts with airlines and hotels, and Kelly recommends opening all of them. As for credit cards, Kelly thinks you can open more than you’d expect:

“You’re told it will destroy credit. It’s not true. If you have a good credit score, there are people like myself who push it to limits. I got four credit cards two weeks ago and eight last year. If you’re not running balances, opening cards will not have a negative impact.” But again, you need to keep track of your spending.

• Transferable-point credit cards: Not all points are equal. A 30,000-point reward ticket might be 100,000 points at a different airline. That’s why Kelly recommends a transferable-point credit card that allows you to rack up points in a central location and use them anywhere. Also, a central pool of points gives you flexibility, particularly if you’re getting rewards tickets for multiple people. Kelly recommends Chase Ultimate Rewards and the American Express Membership Rewards cards.

• Know your cards: Kelly knows people who keep Post-it Notes on their cards so they know which one to use when spending on travel, gas, dining, etc. “Many categories give you double or triple miles on certain categories,” Kelly says. “It pays to keep up with them.”