My advice ?
Don't. Most stores close, and after expenses, most store owners end up making like ten-ish bucks an hour until they close. It's a ton of work, a ton of patience, and the dollars put in will almost certainly yield more money going into just about any other investment.
That said: i salute those that do it. It's thankless, its drama filled lots of times, you're basically never allowed to have a bad day without the unwashed masses kicking up dirt, and at the end of the day it pays worse than most entry level jobs you could get right out of college with a four year degree.
If you're going to do it, and be successful, you need to be a business man first, and a gamer second. Don't know a thing about business ? Stop right now, go take some rudimentary courses at a local community college. The time will never be right to open a business if you don't understand business.
Know what's popular in your area. Cater to Magic and Pokemon as that's almost a given. Understand that Pokemon and Magic pay the bills. Everything else is Gravy, but gravy can be profitable.

Also understand that a pokemon league is like signing up for cheap weekend daycare - daycare that will likely walk in the door with a freshly given 10-20 bucks to spend on packs. It's a downside, but its cashflow. Run magic pre-releases, events, drafts, etc. Again, its lots and lots of constant cashflow (their product is a cashflow dream for a gamestore, a game that rotates its product in and out of obsolescence for some formats in predictable time frames is ingenious. ).
Provide tables to play all games. Have as much terrain as you can muster for the minis gamers. Try to find out which games are hot in your area for minis, really support the hell out of those, expand from there as you can. Get in touch with the Pressgangers in the area, and the equivalents for other games (sorry not sure what they are called) and drum up some interest. Find out the local cons, and even if you can't get a table with product going, go with hand outs for your store.
Know the games that people play, not just the ones you like. You are selling product, which means even if you don't like Bolt Action or X-wing, or
WHFB, there's a customer base out there for it, and you have to drive customers to the product. Know enough about every game you carry to be able to give a 20-30 second explanation on it (i give a pass on board games regarding this).
Do something to distinguish yourself. This is the hard part.
Find out why the other stores in your area closed (talk to multiple sources on this, the previous owner if at all possible, though don't be surprised if he's not thrilled to help you avoid starting your dream of his that just crashed and burnt. Previous owner may also be biased / bllind.). Don't re-create same reasons!
Take pre-orders. BE FASTIDIOUS AND ALMOST ANAL RETENTIVE in telling your customer when its due, when its in. Be the game store owner that tells his customer when its in without them having to ask. I can't stress this enough.
Discourage cliques and hostile behavior by regulars. If you don't know what this is, or can't recognize it, don't open a store. Cliques hurt game stores, and drive money away. If the people with the most disposable income to burn are made to feel unwelcome by the local lampreys that treat the place as their own fiefdom and don't spend a lot of money, you'll drive away business. A group of 10-15 customers can't keep a store afloat is what i'm driving at. If you have a hostile environment due to 10-15 regulars and semi-regulars, and every other person that walks in the door feels like fringe, you'll be closed before you know it.
Plan for the Post-Christmas trough of sales. You need to make enough during the holiday to carry you through the new year. Kids with xmas money may spend some of it in your store, but just as many people will have gotten certificates from befuddled loved ones, or gotten the model as gifts. Seriously, that post xmas trough can murder a store if you're unprepared for it.
Read your lease. Seriously. Know what is required of you as a store as part to your lease in the property you are leasing.
Pick a locale that fills the niche of no other game store within a reasonable area, but still near a population center. Be located near food. Be located convienently towards a major transit highway (as in, within 10 mins drive to a highway or so... varies region to region, really... basically this bullet is "Be Convienent to get to in as much as is possible").
Be a businessman first, a gamer second, or save yourself a lot of time, debt, and heartache, and just light a few grand on fire right here and now. I can't stress this enough. Game stores run by gamers interested in being the captain of their own clubhouse first are doomed unless they have a unique leg up (i.e. - own the space their in, so no rent overhead, etc). Game stores run by competent businessmen and managers end up doing pretty well.
... and about 500 other things... It's a really rough business model, so i wish you luck. Hopefully you continue to love it if you get into it.