* Use an obfuscator to minimize the size of classes.
* Minimize resource sizes by using as few images as possible, and using fewer colors in the images you do use.
* Use as few objects as possible.
* Dereference objects (set them to null) when they're no longer useful so they will be garbage-collected.
* Catch OutOfMemoryErrors on all allocations, or at least the large ones. Don't let an OutOfMemoryError take your application by surprise.
* MIDlets use three types of memory: program memory, heap, and persistent storage. Each of these may be scarce and they should all be treated with respect.