1)Win, be at the top or get to the finals/win a Cup: The team sold a ton of seasons after the 2007 run and they lost a few when the team tanked. This is a town that loves a winner, give them one.
2)Incentives, fluff, that sort of stuff: Invitation to warm-ups, to Senators At Your Service, dibs on new jersey designs, parking spot discounts, etc. Whether it's the Senators or a club membership or a subscription of any kind, people love the perception that they are getting a "Deal". Just for example, I was on public transit the other day, ad for a newspaper. X Weeks for only $30! Y weeeks for $25 plus free access to the papers's Sunday web edition! It's probably still not worth it but at least it catches your eye.
3)Do not, ever, let the ticket go cheaper than what you paid for it: This is a real dealbreaker for some people. If you paid, say, $80 a seat for your seasons and then you open the paper and seats beside you are on sale for $50 or $60, you're upset. Why pay more for the same seat?
4)Better marketing. Back in the day they had the hilarious commercials: "Shoot it Yashin like it's going out of fashion. Let's go Alfie, go top shelfie." They were cheaply made but they were funny and at least got us interested in getting a season package.
5)Kill the negative branding, prop up the team through radio and so on: This is espeically true for the Leafsl, but local radio spend too much time slagging the Leafs, Habs, whomever and not enough time on the team itself. It's like they're insecure or something. Open Team1200 the other day and I hear Zenon Konopka throwing some shots at Alfredsson and so on. A)Why am I hearing Zenon Konopka on the radio? He sounds like Don Brennan B)Why isn't that an Ottawa Senator talking about the upcoming season?
6)Create the illusion of scarcity: We all know they have 10,000-11,000 diehards. What we should hear is how there are only a handful of seasons available for the 2013-2014 season. If we don't get a package we can't be guaranteed seats to see X, Y, Z. Oh, and if you get a season package we'll give you Y to sweeten the pot.
TLDR: Senators marketing are super lazy. They know it's a hockey market so they don't have to try, they consequently don't try and they hope each game is enough of an event to draw people.