First, understand the difference between the two types of small business startups. There's the MBA driven startup where you attempt to acquire millions of dollars of other people's money to create some sort of product or service to then spin off or sell to the highest bidder. The second type is a privately funded (mostly you), shop or service provider in which the owner wants to carve a niche out of an existing trade. These second type of startups are considered lifestyle jobs. I hate that term, but it's true.
A game store is a lifestyle job when compared to the motivation behind the MBA startup. Nobody starts a game store to get rich or innovate in some interesting new way. You can run a really good store, with excellent customer service, and some minor innovations, and you may even scrape by making a living at it, but it's not going to make you the money you could have working any other professional job. You also don't get the high risk, high reward ratio of the MBA startup. It's high risk (for you) and low reward. In other words, it's financially irrational. Just know that going in.
Second, understand why you want to start a game store. Hating your current job is a really bad reason, as is coming into a bunch of money. What I found after owning my own business, is that I really like being a small business owner and working for myself, but ... it wouldn't have required owning a store. If you're tired of working for the man, before taking a vow of poverty and tying up every dollar you and your family have in a game store, investigate if you can do what you do now for yourself. Be the man. You may even make more money at it, eventually.
Games are great, but a good store owner generally plays fewer games because of their time constraints with running a business. Wanting to play more games is a bad motivation for owning a store. In my case, I could have quit my IT job and lived off savings for several years while building my client base. I would have had a LOT of free time to game. If you've got money to open a store, you've got more than enough money to try something like consulting, or even going back to school.
Third, plan. Write a business plan. If you can't organize your thoughts in a business plan, your eventual business will probably be equally scattered. A business plan also forces you to understand the finances of a retail store as you project your sales. Once you've got a plan, carefully choose your location based on how it will fulfill your plan. If you've got a solid plan and capital, you should be looking for the perfect location to implement that plan.
I can't tell you how many stores I've seen over the past five years that just make no sense when you consider their location choice. It's a tragedy when you consider all the money they wasted. My store is 25 minutes from my house. Why? Because my local demographics are all wrong for a game store and the nearby communities of Berkeley/Oakland are over saturated with stores. Research said Walnut Creek/Concord needed a good game store.
Finally, understand what owning a store entails. I've heard it said many times before, but try to work in a game store for a while. If you think this is beneath you, you have no idea what's in store for you. Owning a store is a fantastic adventure, but it's an adventure in humility. You will personally vacuum hundreds of square miles. You will be the guy who cleans up the puke in the bathroom. You will work long hours for little pay and your customers will insist they do you a favor by throwing money your way. You will be brought low. You will take a vow of poverty without the support of a spiritual community or the knowledge that you're making the world a better place. The only people who will understand you are other small business owners. The only reward, really, is the satisfaction of a job well done; a job done your way. But you know what? That satisfaction grossly outweighs all the negatives. You can't beat being excited about going to work every day, of loving your life, of being healthier because you have more happiness in your life. Just make sure there's no other way to accomplish this than owning a game store.