Do your campusfrance application early. If you don’t get your confirmation before going to the consulate, you won’t get your visa.
Expect to travel at least every other weekend. Metz does not have too much to offer, although there are some great things to do there.
Get a Eurail pass. It makes travel much easier, and you will end up saving money.
Get a VISA credit card and find a bank which allows you to use ATM’s without fees.
Fly into Luxembourg. Life is easier, and it’s worth an extra hundred dollars or so.
Arrive in Metz on a weekday. Fabrice, the guy who runs the dorms, won’t let you check in on the weekends, and you’d either have to stay in a hotel/hostel in Metz or find another GTL student to stay with.