Need help with train plans for Venice to Varenna

120 days prior tickets go on sale online.

Train reservations can't be made before 120 days of the travel day. The earlier you book, the greater the chance of getting a super economy discount ticket.

No need to reserve ahead if you don’t want to. You can purchase at the station when you go.
If you purchase ahead however you can save some money with an Economy or SuperEconomy fare.
But be careful. Discounted tickets are restricted. No refunds and no time changes once you purchase a specific train ticket.
www.trenitalia.com
Venice station name is VENEZIA SANTA LUCIA

Realize also u will need to go to Milan station to pick up your train to Varenna.

Also the train to Varenna is a regionale so there are no reserved seats and no savings on an advance purchase. Your just as well buy your tickets in Milan. You must validate your tickets before you get on the train.

Also, there are no ticket machines or manned windows in Varenna. You must buy your return ticket ahead of time (in Milan?).

Additionally, the train only stops for one minute in Varenna. You must be ready to get off/on when it stops. There is no time to spare especially if you have much luggage.

We just did that - took a fast train from Venice into Milan, then got on the regional train to Varenna. We reserved our first class seats far in advance because the price was great. Once in Milan, you can purchase your ticket to Varenna. The train ride from Milan to Varenna is about an hour, and like someone else wrote on this thread, hop off quickly once you get there.

I visited Varenna a few months ago. There is now taxi service to/from the train station. With luggage or rain, the 10 euros are worth it. I would buy both tickets in advance if you can. Milan train station is big and can be confusing, so get yourself oriented and maybe buy some food for the train.

Thanks to all of you for your very helpful responses! Will start looking at train schedules now!