I use Google Calendar for timekeeping and different GMail accounts for email management. They can all be linked to one account, so that you don’t have to log in or out (or, you can have different mailboxes set up for your employees and still be able to access them). Then, each one can be filtered, so that there is a label attached to a mailing that arrives to/from a particular account.
Yes, this is really good idea to use Google. It has so many features which would work as tools.
And in freelancing, these are the main tools:
Communication
Discipline
Knowledge of Work
Completing work on time
Understanding Your Clients
How to manage over work
How to manage assistants under you
How to provide quality work at competitive prices.