I want to do someone else's tax return. How do I start?

[LaShaunA3]

If you're using TurboTax Online, each Intuit account allows you to e-file one federal tax return, and up to five associated state returns.

With TurboTax Desktop, you can e-file up to five federal returns per software license, and each federal return may include up to three state returns. 

[VolvoGirl]

You can start another return in TurboTax Online by:
Logging out if you are in your account
Choose what TurboTax Online product you want to use for the second return
https://turbotax.intuit.com/personal-taxes/compare/online

Create your account screen
Set up a new login for the second return
Start working on the new return