I want to purchase tickets for the last game played at Yankee Stadium and Shea Stadium. Thanks for your help.

Each team picks its own time to announce their schedules. Several teams have already publicly released theirs, but others are holding off.

Ticket sale dates, too, are done individually - for single games, the date is usually sometime in January or February. Your best bet is probably to sign up for the email list of the teams you're interested in and they'll let you know when ticket sales start.

I've never bought tickets for games at either of those stadiums, but for Camden Yards, it's usually sometime in January. You might want to see if there's a list you can join to get news about the team - you may get advanced ticket notices, a sort of pre-sale deal :).

Most teams released their home schedules this week. You can put down a deposit for season tickets, but otherwise you will have to wait until February to buy individual game tickets (that is the normal date, though the NY teams may have different rules).