How do you stay organized?

What methods do you follow to keep your client records in order? When you have a long list of clients and limited hours in a day it may be difficult to manage all the information. How do you make sure you keep track of all the little details? Share some of those handy tools that keep you on-task, on-time and organized. Maintaining a day-planner, organizer or online calendar can be helpful and necessary. What tools do you prefer?