I've been going to this for ~30 years, it's one of my favorite times of the year and I am truly going to miss it. I've collected a lot of items from it over the years, I have an order form for the 1983 tournament (first one at MSG) that says (and I quote) "The Package Ticket provides admission to all five sessions, eight games of the 1983 Big East Championship for $50 and $2 handling charge". Those were the days!
In recent years I've tried the package, other fans and Stubhub for tickets. There's a downside to each and probably the reason that I don't have a surefire plan from year to year. I'm happy just to be in the building, I've sat in 400 level seats many times, it's not for everyone but I don't mind them. One flaw in the 300 level seating is that if you sit near the front of the section, the walkway is right in front of you and people walking by constantly disrupt your view -- I don't know if this has been addressed at all in the MSG remodeling that went on over the summer. In the past I used to go to all sessions (pre-expansion to 16 teams), these days I only bother with sessions where SU plays.
As for the tickets, sessions with SU drive demand greatly, it's remarkable how much more you'll pay for an SU session than a non-SU session. And if/when they get knocked out early, the prices drop like a rock. I bought a package last year and took a small bath on it, nobody wants the Tuesday tickets, and I found it was hard to even get face for any non-SU sessions, and I even had to eat some 400 level seats for Wednesday. I also lost money on tickets for the title game once SU got knocked out, I think when it was all said and done I ended up spending about $275 for seats for the Thursday and Friday games after what I was able to sell from my $450 package, and I had to work to get rid of tickets I didn't want.
You can certainly try shmoozing with other fans and trying to get tickets that way, I've had luck there at times, other times it can be a challenge. I've gone with Stubhub in the past and I'm planning to do it again this year, just on an individual session basis. I tend to go with a group of at least six people, when you buy in that much quantity the markup on what the seller is asking for isn't so bad, maybe like $5-6 a ticket as long as you can get them all in one transaction. I wouldn't bother buying now, wait until closer to the tournament. I would guess that 400 level tickets for SU in a Thursday session will start a little over $100, expect to pay a bit more for better seats. Friday night tickets, before SU officially advances, will probably be closer to $150, and if you wait until they advance, expect to pay $175 just for 400 level. If you have Friday tickets and SU gets bounced before Friday, they will drop like a rock in value; when it comes to ticket value, in my experience you just can't win if you're an SU fan. Saturday tickets tend to be the easiest to get relative to face value, of course face on them is like $100 IIRC. I have no plans to continue this in the ACC era (unless it moves to MSG one day), I'm willing to overpay a little more knowing that these days are numbered.
Good luck to all you first timers, and enjoy it while you can.