For newcomers to Mongolia who are looking for an adventure, if you are looking for travel agencies that serve French speaking nationals, you need to find an agency that has fluently native French tour guides, directors, and an agency that is dedicated to providing you with excellence.
When choosing a tour agency, it is a MUST to choose tour agencies that you will trust and that will give you an authentic experience for the whole trip. Try Google-ing the best tour agencies; I am sure you will find a few.
When it comes to traversing the Mongolian roads, your tour agency needs to have vehicles that are built to go off-road. If you are more of an adventurer and like old-school things, there are some drivers who will give you the authentic 1990s era Mongolian feel. Old Russian cars, although most are replaced by Toyatas nowadays, you can a find a few Russian 69, Porgon.
However, choose an agency that is best suited for your needs. If you need a bigger bus to tour around the country, most agencies will not be able to go off-road with those big buses. If comfort is important to you, it is best to look into tour agencies that has newer cars that are built to go off-road such as Land Cruiser, Range Rover etc.
Mongolia is a place for travellers seeking an experience and adventure, so if you go outside of the capital Ulaanbaatar, your chances of staying in nice 5 star hotels with modern day luxuries is very small. Lodging is limited to more like motels, hostels, guest houses, etc outside the city.
For a more authentic experience, you can bring your tent to camp out during the night. Just make sure you are camping out during the summer, otherwise, the winter is very cold and harsh. However, it is best recommended to stay in a Ger or (yurt) to get the nomadic experience of staying in Mongolia.
You can bring your own food and it is advised to bring your own snacks in bulk beforehand, because you won’t be able to get off at an exit just a few minutes away from the highway. Some shops can be closed during the day and some villages don’t have sweets or don’t have a wide selection of snacks.
If you happen to a vegetarian, your choices are very limited, but there are tour agencies that cater to vegetarians; thought it is going to be difficult to find food from the nomads since the nomads live off of their livestock and the products made by their livestock.
So just make sure to keep those things in mind when making your decision and factor in the cost of the tour as well.