the comic shop closest to my home [in PA, not NY] has a 20% discount on new issues, back issues and trades for subscribers. subscribers just need to have ten issues on their monthly pull list, which is like getting two of those free after discounts. most collectors buy more than eight comics a month, so that's not really a big stretch.
the next closest sucks. it's full of the battlehammer, magic, RPG, card games stuff. and it's not bad that those are there, i know they often go hand in hand. but the way the customers who play those games act, and yell, and the way the employees often step away from their jobs for half an hour to play a game with some kid [completely ignoring the shopper who came in, browsed the comics, and has a handful of cash ready to pay] makes it unbearable. if you're going to take that route, make your employees keep their priorities straight, keep the in-house players from shouting or acting like dicks, and generally don't hire shitty people.
that's just a big point. have a helpful staff that reads comics, but doesn't talk your ear off with their opinion. i didn't need to hear half an hour's worth of raving to understand the guy liked astonishing x-men, and it actually turned me off from buying it, or shopping there, again.
comic-related merchandise is always helpful. the comics and more shop in the king of prussia mall has a great selection [i've only been looking for two back-issues i couldn't find there, and i've looked for hundreds,] and they have shirts, toys, collectors items, etcetera. they also have a specific section for the all ages comics, which is considerably smaller, but also very well organized, updated and generally in good shape. if i had kids getting into comics, that's the first place i'd shop with them, just because of the seeming respect they give to the often-overlooked all ages comics.
nothing's going to be better than having a big, healthy selection of back issues, and a great display system for the more current issues. i don't remember the shop's name, but some big store in the middle of ridley, PA [voted best comic shop in the delaware valley three years running] had all of the more recent issues of every comic imaginable lining the shelves along the outside, and a neat, aisle-like series of backissue bins, actions figures and other merchandise throughout the middle. it was, by far, the best store i've been to in terms of selection, though their sparse staff and gang of regulars made newcomers like myself feel a bit out of place.
good staff, good selection, none of that bullshit, and enough corresponding merchandise layed out to make the shopper's eyes roam should do you some good.
best of luck. lord knows we could always use more stores.