Step four is comparing all of the above steps for all magazines that are in contention for your ad dollars. Make a spreadsheet. Steps 5 and 6 are settling on the primary magazine that you will use to carry your message to your target market, calling the rep in and negotiating. Don't keep changing your ad plan. If you studied it, pored over it, gave it your best effort, then you must give it a chance to prove itself.
Advertising requires patience and maturity.
I think I finally know enough to advise existing and prospective advertisers on how to be most effective in choosing media. There are some tricks to this, but for the most part it's common sense. Once you know how to look at readily available information your advertising expenditures will be far more effective and buying advertising will be far less unpleasant. Some part of being a better media buyer is attitudinal. You don't have to tolerate harassment from space reps or publishers.