How can you reduce the amount of memory required in an embedded system?

"There are several different techniques you can use to reduce the amount of memory required by an embedded system. Some of these include factoring your code, only returning values when they are necessary, making a large number of calls to a small function as opposed to a small number of calls to a larger function, and using as many local variables as you can, reducing the number of system calls and memory usage. All of these techniques work, so I use the ones that are most applicable to the function of the Tesla system and the type of code I am writing."