Hay Day is one of the most popular free to play games on the App Store, but it'll cost you a bundle in in app purchases if you're not careful. Here are some tips I've figured out on how to get ahead in the game without paying a dime.
Hay Day puts you in charge of rehabilitating a farm that's seen better days. You grow and harvest crops, raise livestock, clearing land, and make goods you can sell to local businesses and consumers to make a tidy profit. With each new level comes new goods you can make, new livestock and crops, and some other assorted goodies to help make your farming experience better. Like most free to play games, there's an in app purchase mechanism that you can use to buy a hard currency in the game (diamonds) which will get you ahead and get you out of jams. The tips I've come up with are to keep you out of those jams.