What tools do you use to keep track of your freelance orders and clients?

[Shortie]

As a freelancer, you soon realize, especially if you start to get regular work in and clients that it can get a little hectic and you can get confused and lose track of what you have and have not completed.

With issues like this, it is always wise to have a method in which you can keep track of work completed and clients that you have to prevent any issues that could affect you getting regular clients.

What tools do you use to keep track of your freelance orders and clients?