When Glen Zubia graduated from the University of Texas at El Paso in 2009, he had just over $50,000 in debt between student loans, a car loan and credit cards. For the first few years, he worked as a graphic designer and made the minimum payments required. Then, three years after graduating, Zubia got more serious about extinguishing his debt and started buying sneakers, sports jerseys and video games he could resell through Craigslist, eBay and other sites. [See: 10 Easy Ways to Pay Off Debt.]Four and a half years later, Zubia had paid off his debt thanks to his resale hustle on the weekends. He also launched Hustler Hacks, a website and YouTube channel where he shares his strategies. U.S. News recently spoke with Zubia about his passion for reselling online, how he spots a good buy and his future goals. The following excerpts have been edited for clarity and brevity:How did you get into the resale world?I signed up for eBay around 2000 or 2001 as a little side hobby. I started off with football figures. I would repaint them as certain players that maybe weren't on the market and sell them. I just wanted to do something different with my art I guess, so I started making money doing that. Once I started college, I stopped for a little bit, and after I graduated I had student loans, so that's when I really started taking it seriously. What mistakes do you see in reselling? A lot of people want to make money really, really quickly, and I started off really slowly, just doing garage sales, Craigslist and eBay selling. I didn't want to spend a lot of money at first. I followed a buy low, sell high mentality, and just did whatever I could in the amount of time that I had. How did you know before you bought something if you'd be able to sell it for a higher profit? I started by researching things on the eBay app. They have a completed listings filter that allows you to see what certain items have been selling for in the past month or so â€“Â what they've actually sold for instead of just whatever price people throw out there. People think that just because someone has it out there on eBay that it's going to sell for that much. Even while at a garage sale, I would research the things that caught my eye. I like to tell people that what you know and what you have knowledge of is really what you should start off with. I like collecting sneakers, and I was always into sports and the NBA, so I knew certain sneakers that were worth a good amount of money, along with jerseys and also video games. [See: Your Month-to-Month Guide to Savings.]How do you balance reselling with your day job?That is probably one of the toughest things. On Friday nights, I would list things early because on Saturday I was always going to garage sales, flea markets, swap meet type things [a gathering where collectors trade items]. I would get up at like 4:30 a.m. and then I would be doing all of that stuff until maybe 1 or 2 p.m. I really try to utilize weekends because Friday night, Saturday and Sunday are specifically for reselling. Any tips for others who want to get into reselling?I think it's so important to diversify your income. So many people get laid off or fired, and if you're just relying on that one check, you are going to be in trouble in trying to figure out what to do next. I think it's so important to diversify your income and look at these opportunities that are out there. Everything is at your fingertips. You can look up any item whether you're in a resell store or thrift store and see how much certain things are worth. And it will take some time to learn reselling, but I just think it's important to diversify your income so you're not in panic mode when something happens. Now that you've paid off your debt, what's your next goal? I've started dabbling on Merch by Amazon [an invitation-only platform that allows Amazon users to create and upload their merchandise]. They have a business where I can upload my graphic designs and they make them into T-shirts, so I have been doing that. I'm getting married next month, so my goals have now changed to paying off my house. The good news is that I'm able to tackle debt totally differently than before I started reselling. [See: 8 Financial Steps to Take After Paying Off a Debt.]I reinvested all the reselling money into the reselling business or it went straight to these loans. While making those minimum payments, I just kept thinking that they would probably never go down because of these interest rates and everything with the student loans, but now with the reselling side hustle and making extra income, my next goal is to pay off my house in 10 years or less..