Hardware

The first thing to do is to check your hardware.If you have an old Mac it means you have old parts.The easiest way and cheapest part to upgrade is your RAM.

Wasted Hard Disk space

Take a look in your applications folder.Determine whether you need all those applications.Get rid of all the programs you feel aren`t worth keeping.

Delete Language Packs

Delete languages that you don`t use.Monolingual helps getting rid of the languages a breeze.

Clean Out Your Startup Items

In order to change the startup open your System Preferences and click accounts. Select your username, now you are able to see a list of startup items.Getting rid of them will speed up every time you boot up your Mac.

Clean Up Your Desktop

If your desktop is covered with a field of icons it is a good idea to clean it up.Mac OS X treats each desktop icon as its own window which will affect your RAM.