Observe your Weekly Merchandise, TV Contract... coz they will improve.
Scout your Leaguemates' Arena and Observe there Seat count, Pricing and attendance... that could give you an Idea how you can adjust and improve yours...
ex:
https://buzzerbeater.com/team/32792/arena.aspxType: Bleachers| Lower Tier| Courtside Seats| Luxury Boxes
Attendance: 14739| 2345 |500| 16
Price: 13| 40| 100| 1200
and I have read somewhere here in the forums... that you'll have some Bonus Ticket Holders or something... Go forth and search more :D