Summarize the following:
Before you start overclocking, you'll want to make sure you are running the latest drivers on your video card. You can download the latest drivers from the Nvidia or AMD site, depending on which manufacturer you have. Having the latest drivers will ensure that your card is running as stably as possible. Newer drivers often increase overclocking performance as well. To overclock, you will need a few different programs, all of which are available for free. These programs will give you performance benchmarks, allow you to adjust your card timing and voltage, and monitor temperature performance.  Download a benchmark program - There are several available, but one of the quickest and most intuitive is Heaven. It is available for free from Unigine, the developers. Another popular program is 3DMark. Download an overclocking program. While both Nvidia and AMD have overclocking utilities of their own, MSI Afterburner is one of the most popular and widely-used programs. Despite it's name, it will work with virtually every graphics card from both Nvidia and AMD.  Download a monitoring program. Although benchmark and overclocking programs will report temperatures and speeds, sometimes it's good to have another monitor to make sure that all of your settings take. GPU-Z is a lightweight program that will monitor the temperature, clock speed, memory speed, and every other aspect of your graphics card. Going into your overclocking process without being informed can cost you a lot of time and cause you a lot of headaches later on. You want to find the clock speeds that other users who have your exact same card are getting. You also need to find what is generally considered to be your card's highest safe voltage.  Do not immediately apply these numbers to your card. Since every card is different, there's no telling what could happen if you enter the wrong numbers. Instead, use them as a guide during the overclocking process to judge how effective your numbers are. Try forums such as Overclock.net to find other overclockers who have the same card that you do. Overclocking a laptop's GPU is not recommended. Laptops have a much harder time dissipating heat, and overclocking can quickly lead to dangerous temperatures.

Summary:
Update your video card drivers. Download your tools. Research your card.