The Magazine Publishers of Australia (MPA) have put together a great on-line site about magazines for advertising agencies and marketers. It has some great features for newsagents thinking about doing category analysis on their products.
One tip I can give you is when you talk to magazine producers they are always talking demographics and magazine categories, so keep that in mind while using this screen. The logic here is for an advertiser of a product, not a newsagent. Having said that they have made it easy for you on this screen to put in the various population segments and then you to study what types of magazines should go well in your area. Then it is up to you to see why they are different.
Having said that I doubt there will be any surprises to anyone as the best magazine buyers are young, socially aware, big spending, and intelligent women from families with good incomes. I suppose the question now becomes is your shop the place where these women would want to shop for magazines?