Sorry that this is too late to be useful this year (I just signed up for the MBs), but if anyone is going in the future, maybe it will help.
1) Learn a little French if you don't already know some. It is much more respectful, and people appreciate it, if you speak to them in their own language. Always say "Madame" and "Monsieur", as in "excuse me, sir, could you please tell me if this is the RG metro stop?"; it's considered rude to ask people questions without using these modes of address.
2) Unlike the grounds of other tournaments, RG is ALWAYS crowded and this can be stressful, especially if it is hot. There is a little park just east of the RG grounds that is NOT crowded, and I think it is very inexpensive to enter. Depending on the type of ticket you have, you may be able to leave, take a de-stress break, and return. It's very nice to escape and sit on a quiet, shady park bench there and feed a few pigeons.
3) RG is very easy to get to from the metro. So find a nice inexpensive hotel near a metro stop, and you are good to go. I would stay away from the touristy areas due to the expense.
4) You cannot get a bad meal in Paris (unless you go to McDonald's). What an amazing culture.
Have a great time!