Hey - it's actually really easy. Really!

Every RER platform has lit-up signs with stops along that line. If the train stops at the station you want, the little light bulb is lit next to the station name.

There are a couple of Versailles stations ('cause it's a big town), and you want the Versailles Rive Gauche stop - it's closest.

All RER trains have 4-letter acronyms, most often names or weird words, on the front. This is for locals, who would know that VICK or whatever is their express train . . .

We always like to make up other 4-letter words they could use as mnemonics instead

Enjoy the bistros & bars in centre ville, too.
Hope this helps - you'll have a blast.

We are also planning a trip there in May. We will be there for the first sunday of the month. Is entrance free on that day for Versailles or is it just the paris museums. How crowded would it be on a day like that.
I will have a museum pass for the monday, tuesday, and wed. Would it be better to go one of those day.
Thanks in advance.

Hey MD-

Do not worry. People are very friendly there. It was very easy. I don't think they ever came around asking for tickets. I was scared also when my sister and I went but it was very easy.
Be careful there of the gypsies. My sister being naive that she is got circled by a group of young gypsies. I grabbed her hand and just stared them down and got her out of there fast before they could do anything.

If you want Versailles without crowds, it won't happen. It can indeed get packed. However, if you want some of Versailles without crowds, go before the palace opens. You can still stroll around the gardens, along with the few other visitors who will be there at that hour, and you can get in on the first tours of the day without waiting in a long line and without having to elbow your way through the palace. We found that it really got crowded by mid-morning. It is worth it to head out from Paris early.