When you first arrive in the city of Lausanne you need to stop by the Lausanne Tourisme, which is a great little shop inside the main train station which has all the information you need about the city and places to go and things to do in Lausanne. The maps of the city there are free and you can find out all the bus info and cards to ride. There is also information on the museums and passports available to go to the museums.
The Lausanne Tourisme is a must stop when in the city because it will save you so much time and hassle by telling you all you need to know about the city upfront. The Lausanne Tourisme is a good place to reserve hotels or if you are planning on staying in the city longer term there is a long list of furnished apartments one can rent in the city.