How do you tip?
The Guru Take
Often cash, but some rideshare companies allow you leave it within the app.
With Taxis and Limo drivers, it's customary to tip with cash at the end of the trip.
With Lyft, you have the option of leaving a tip on the app, where you can specify the amount to be charged to the credit card on file. (With Uber, as they promote the "cashless experience," there is currently no option to leave a tip within the app. With that said, many people, often on UberX, do leave tip with cash.)
UPDATE: Uber now offers In-app tipping:
Here are other useful threads.