Housing and (mandatory) health insurance will probably form the top-two expenses when you come to live in Switzerland.
Where
Finding a place to live in the larger cities (Geneva, Basel, Zurich) can be extremely difficult - paying for your home even more, as house and appartment prices can be sky high. If you are on a budget, you will probably not be able to allow yourself a home in these cities. Be aware that public transport is excellent in Switzerland and commuting is easy and more affordable: search for a place outside the big cities and you may be more lucky.
Rent
Renting a house or appartment usually requires a deposit of 2-3 months of rent. The deposit should be placed on a bank account on your name (not the landlord's!), the access to the account should only be possible for you and the landlord together.
Find houses and appartments on the internet (, ). Houses/Appartments are usually counted by the number of rooms, living room included. A "half" room means, that the kitchen is large enough to contain a dining table. So a 3.5 room flat will usually have 2 bedrooms, a living room and it will be possible to eat in the kitchen. In a small town like Olten, expect to pay at least 1'250-1'400 CHF/month for a simple, small 3-room flat. In Zurich, you can easily pay 2'500-3'000 CHF/month or more for the same flat.
Rental contracts usually are for minimal 1 year, and you can cancel your contract usually at only 2 or 3 fixed days per year - with 3-months-notice in advance. If you want to leave earlier or inbetween, you'll have to find a suitable follow-up renter or pay the rent yourself.
Rent usually includes kitchen appliances and use of a washing machine and/or tumbler. Costs for walls and floor cover are included in the rent - replacement of them is paid for by the landlord.
Particularly in older or cheaper appartment blocks, it is unusual to have your own washing machine and tumbler. These facilities are shared by all who live in the same block and it may be the case that you can use them only for one or two half days a week. Good planning required!
Older places can be noisy and as Swiss are very keen on their rest, sleep and peace, there may be quite strict rules ("Hausordnung") on noise, showering or using washing machines after 10pm or before 6am, pets, etc.
Swiss are quite strict on regulations. Therefore, check your rent contract before you sign it. If you want to hold a pet or play an music instrument and the contract doesn't allow it - ask the landlord for an amendment before you sign. The same if you want to install a satellite receiver on the balcony.
Students and other young people with low incomes usually rent an appartment with 2 or 3 together, to save on rent costs. This is called a "WG" (Wohngemeinschaft).
Buy
As house prices are high, relatively few people buy a house or appartment. Mortgage interest rates are at a historically low level, but you'll have to finance 20% yourself, and that is the biggest hurdle to take when you want to buy your own place. The bank won't give you a mortgage higher than 80% of the value of the house. Find places on the internet (comparis.ch, immoscout24.ch).
Nevertheless, demand on the current market is larger than supply and it is not easy to find a suitable and affordable house.