Give yourself a month or more to prepare your applications. Your applications will need to be ready by December of your senior year of high school, or October of your senior year if you're applying early decision or early action. Be sure to allow plenty of time to prepare materials, including your essays, test scores, recommendations, and other supplementary materials.
Check to see if the schools you're interested in accept the Common Application. This is a standard college application form offered online and in print that more than 400 colleges and universities accept.
The Common Application is designed to make it easier to apply to multiple schools. For example, once you enter your profile information you don't have to enter it again for the next application. Also, most online applications allow you to fill them out at your own pace, and allow you to save them and return to them later if you don't have time to fill them out in one sitting.