So this means that your application, usually can't take more than 50 to 60 Mb of RAM.
For myselfs I've put some guidelines to manage that limitation :
1. Never use more memory than needed for the view you are in, so release, release
2. Every viewcontroller should be released as soon it's pushed in a navigation controller
3. Use proxy's (lazy object creation)
4. use SQLite for caching (store your objects in a SQLLite database, this database is not using RAM)
5. Prepare your application for the worsed and implement the didRecieveMemoryWarning method