You've gotten some very good advice. Congratulations on your first trip.

Depending on the time of year you may get your room when you arrive. We've been 6 times and got the room right away 4. They'll let you leave your bag at the hotel.

We are usually too wiped out (it's a long flight from here) to attempt much the first day.

One caveat about the train - the TGV (train à grande vitesse or train of great speed) is not all that luggage-friendly, so traveling as light as possible will make it easier. It's great fun, though. I wish we had a system like that.

Be sure to get a good guide book. Some folks here dump on Rick Steves, but his book is a good intro for a first time visitor. You can find some good hotel discounts in his Paris book, so we get it just for that.

Find an ATM at the airport and get some euros. Maybe €300 to start.

I would not take the RER on a first visit to Paris. I'd take a taxi. It will cost maybe €45 to €60 depending on traffic and how much luggage you have and other mysterious factors.

Whether or not you have a backpack or a camera around your neck, everyone will know you are a tourist. It's the shoes, I believe, or the haircut, or just the attitude. In my case, I'm too tall, I have an American haircut, and while I have Italian shoes, they're brown, and nobody wears brown shoes. Jeans are very popular, but they are just a little different.

If you are approached by some gypsies saying 'doo you speeek eeengleesh' tell them very firmly to go away. Preferably in German. If someone picks up a gold ring off ground in front of you and holds it up, do the same.

All hotels have safes in the room in my experience.

Bon voyage!