A lot of photography revolves around your ability to be prepared when the moment strikes and be able to adapt quickly as the scenery and required settings change. One of the best ways to be more efficient and increase your chances of getting the shot is by using custom controls, which this great video goes into detail about.
Coming to you from Mango Street, this awesome video will show you a few quick tips for making your camera work faster. Personally, I think the most important is custom modes. These allow you to enter any number of settings: shutter speed, aperture, white balance, AF, metering, etc., and quickly return to exactly the values you want just by calling up that custom mode. If you work in situations where you have to get a lot of shots in a short period of time and the light and action are constantly changing, these can be an absolute lifesaver. For example, imagine shooting a wedding under a tent on a sunny day, then following the couple as they recess into the sunlight. Instead of scrambling to change all your settings, you just turn your mode dial once and you're ready to go. I honestly can't imagine shooting without them at this point.
My Canons all have three custom modes, but frankly I could use 5-8. But I put my custom mode registration on My Menu so it's easily at hand and simple to reprogram as needed. I've used these for over 10 years and they are priceless.
Canon. Good to know if you have a different manufacturer's camera.