I found that having lower deck at $50 and upper deck at $25 got me more money/attendance. Also use promotional days on weekdays and against teams with less than 5/10 game impact. Buy more than 1000 of whatever promotion you have. Try lowering upper deck to 20$ against poor teams or if your attendance is low. Look through your roster for low performing/high contract players.
For instance: I own the Dodgers, I've traded Hideo Nomo(I like his pitching but have no use for him on my roster) and his $3.1 million dollar contract for a decent mid-twenties $500-$300k player, just saved 2 million. Do that several times.
When Game impact is at 6 or 7 up your prices to 55 / 30 or 60 /30. To learn how your team can make money, I suggest saving your game and setting prices while noting how much money you have, then simulate the next game. Reload your save game, change prices around and simulate again. The things to look for are Daily Finances - it shows you how much money you lose/make on a daily basis - look at it after a home game. If you make more after a home game than you lose on an off day or an away game, your making money. After this method I had close to 4 million after a long homestand in May!! Its tedious to load, set prices, simulate, check money, reload, etc. but it worked for me. Try to get 4 million before the season is over and upgrade stadium seating to 25000 then you'll be making cheese.