There are many tools out there for optimizing your Mac.
If you look you'll find ones like Cocktail, Mac Janitor and TinkerTools. They are all very popular and great but my favorite is Onyx.
Onyx lets you do a variety of "Cleaning" and "Repair" tasks that will clear your Mac of all it's crap. It has been debated how effective this is, but I find it does the trick.
In Onyx there is a long list of things you can clean. You get to choose what options to run. When choosing make sure you know what your doing so you don't have any problems.