Shop around. I've noticed that the prices are consistent from site to site. Where it gets iffy are the bad 300 seating, where some sellers will try to dump their bad tickets out of fear they might be holding the bag in the end. But where and when? There is no one place for the best. Direct tickets offer you one comfort, and that is, if a game gets canceled. Rare, but be mindful if you buy playoff tickets.
Also, know the difference between legitimate scalpers and illegitimate scalpers. A scalper just means a person of small barter/trade. Just like if you bought an iphone6 then turned it around to sell it to a friend or on ebay, you were scalping. It's not always a higher price, but after years of people misapplying the term, people generally associate scalping with higher prices.
The reason I mention scalping, is because you have people in the area(like the parking directors) that will buy tickets off people leaving the game before they start(for whatever reasons, like kids misbehaving, emergency, etc) for fairly cheap, and you can catch them turning around those tickets for a profit, while sometimes under face value. And of course, you have high demand games, so prices are bid up, that's life. Also, other scalpers in the area want to unload tickets so they don't lose money. I like the parking attendant/managers, because they are there most of the time. Here's a good guide if you want to live on the wild-side trying to score off the street(or even using ebay, because really, ebay sellers are just as reputable as any guy on the street, especially now when you can buy a lot of cheap feedback for a few bucks.)
http://blog.ticketmaster.com/concert-counterfeit-tickets/