For the love of all things bright and beautiful, MAKE YOUR STORE AN ACCESSIBLE AND AVAILABLE TO EVERYONE.
That's the biggest mistake that I see killing comic book and gaming stores. Don't shut out women - they're half of your potential audience. Similarly, don't shut out minorities. If you make your comic book store an appealing place to only white dudebros, you're going to die a slow death.
If people are being creepy, ask them to leave. Don't decorate solely with tits and ass statuettes. Throw up Wonder Woman and Miles Morales as Spider Man in the window. And, I'm just gonna say this again, if people are being creepy, show them the door. Make a point to maybe even pick up 'zines and mini comics from local sources. Have a shelf for indie comics and the more well-known stuff like Alison Bechdel's Fun Home. And did I mention not serving people who are being creepy? Because that's the most important part.
Seriously. It's your little kingdom. You make the rules. Have one of the rules be "if you're being a creep, you're out". The person who has his eyes glued to the tits and ass of every female in his presence? Out he goes. The person who is loudly making racist jokes and thinks 'rape' is a hilarious punchline? Tell him to go elsewhere. So on, and so on.
It's good business sense. Don't shut out so much of your potential clientele. Appeal to broad interests. That's the way to succeed, and the way to distance yourself from the cancer that current comic book culture is busy nursing.
As far as more practical advice goes, make sure to advertise around your local colleges and even high schools. Especially advertise event nights that are targetting people who are in the "I've always wanted to get into this, I've just never had the chance" camp. Maybe do something like a short one-day-on-the-weekend D&D campaign with premade characters, with tickets costing 15 dollars to also cover pizza and drinks. A Magic beginner's tournament where you use the ruleset of you only play with what you get from x number of packs (I don't actually play card games like these, I just like listening to people talk about game crafting theory haha), and again use tickets to cover the costs of the packs and some refreshments.
Things like that, basically, so that people who have always wanted to try things can come have a taste that doesn't get them into an overwhelming commitment. Then if even just a small percent of them are hooked, you have new lifetime customers who see you as the person to come to for advice and guidance and already have that loyalty to your store.
Most importantly, though... Best of luck dude! Good luck!! :>