I bought and printed my train tickets from www.voyages-sncf.com.( Paris-Avignon TGV). I got the prems so they were cheap but now do I need anything else, like a separate reservation? The tickets have the seat number printed on it, so I assume I am all set.

You are all set.

Are you coming back to Paris the same way?

For Paris-Avignon leg, the train is already waiting in the platform so you can take time looking for your car.

On the return leg, the train only makes a brief stop at Avignon, so you need to be waiting at the right spot on the platform. How do you know? On the platform, there is a train composition display. Locate your car on the display, find the platform marker id, "repère," and wait for the train at the place indicated by the marker.

Make sure you have a photo ID that matches the info on your ticket. The controlleur on the train may ask to see that in addition to your ticket.

Other than that, you don't need anything else. Just board the train. No need to composte your tickets.

When we were en route from Paris to Reims or to Dijon (I forget which) the controlleur was quite incensed that we didn't have our US Passports with us for ID. He was not impressed with our photo-ID California driver's licenses and for a while seemed inclined to put us off the train at the next stop--but he didn't. That has never been a problem on any other French train trip, but I guess it is always a risk.

Just shows how much things can vary... I handed over our Prems and the conductor glanced at them but waved away the proffered passports!

Thanks for your responses. I will be sure to have my passport available just in case!