I save all my appointment data in my calendar. It seems to work the best for me. I can update what I just did after each appointment and at the end of the week, pull up my calendar and send invoices based on the appointments. Lately, however, after the switch to Apple, I have had to do a bit of double entry as my invoicing is now on a separate system from my calendar.

The Answer? Google Calendar. That way, all my appointment info is on a web-based calendar which can be accessed from anywhere. I bought a $6 app for my iPhone that holds cached copies of the calendar and syncs it all day long. Now I can look at my calendar on my phone, my laptop and any internet connected desktop. I have also linked my calendar to my website. Google gives you the code to embed the calendar. Now, my clients can see when I am busy and schedule accordingly.

I have been using this system for a couple of weeks and it is working fine. Go take a look at my calendar before scheduling your next appointment.