The first thing you're going to need to do is find out when and where (at which stores/sites) the shoe you want is releasing.
For in store purchases the day of the release, the big chain stores would be Nike store, Footlocker (FTL), Footaction (FA), Finishline (FNL), and sometimes Champs. Additionally, there are a few boutique/mom and pop stores you should check out like Bodega.
Note: Most stores do not do first come first serve anymore, especially for limited edition shoes. FTL, FA, and FNL either do a raffle where you need to go into the store during a designated day/time (usually they choose 2 days at the beginning of the week of the release) to pick up a raffle ticket or they do a reserved ticket procedure where you need to go into the store during a designated day/time to get a ticket for a guaranteed pair in a specific size. FTL offers a "Launch Locator" page which helps consumers find out when a shoe will release, which locations will be getting them, and what the method each store will implement for that specific release.
Nike stores on the other hand use Twitter to sell the shoes at their brick and mortar locations. You need to follow Nike Boston (@NikeBoston). They always announce in advance the shoe that they are getting, the date of the release for that shoe, and the day that they will be doing RSVP (almost always the Thursday before the release). You should read Nike's rules regarding how to properly submit a Direct Message for a chance to win [the right to purchase the shoe].
For online websites, you'll want to check out the big chain stores listed above as well as Eastbay (although Eastbay, Footlocker, and Footaction all share the same inventory). Most stores begin selling their supply at 8:00 am ET, however some stores, such as JimmyJazz, releases their pairs at the traditional time which is midnight ET.
This is just sort of the basics, but any other questions can be easily answered by simply calling the stores.
Good luck.
