State your services and send out professional Quotes or Estimates to your clients.
If you add your Terms and Conditions you will end up with a watertight Contract, an invaluable asset for any Business or Freelancer.
Once the work is won, track your activities against your Quote to monitor your progress.
You can see your "uninvoiced" value go up as you add entries... imagine facebook notifications for your cashflow.
After you have accumulated a backlog of Activities, you can then convert them into accurate Invoices.
These can be sent directly to your clients inbox to help you get paid on time!