Have you decided how much it would cost per ad and how much space would be allocated to the advertisee ? You could sell half page or full page ads and since you don't even have a market yet nor do you have stats or any other form of selling tools you should offer a free month or more to potential customers.
Also, where are they going to be sold ? At local kiosks ? Convinient stores ? Army Surplus stores ? I could sell them for you in Montreal ... you might have to translate the magazine into french as well, or have a french section which i could help you with. Discounts should also be offered to resellers.