My tip would be to read as many threads, in this forum and in others, about the rules and regulations for starting small businesses. In that way, you will learn from the mistakes of others, and can plan carefully, long before you actually spend any part of your starting capital.
For example, these threads, and the many links in them, may give you some ideas about the formal side of things:
Working on your own, what kind of license do You need?
and
small company registration, self business
and
Home cooking business and kitchen inspection - Zuerich
and if you and/or your friend are "non.EU", then
Immigration status of Non-EU starting a business in Switzerland
Oh, and well done that you are both learning German! That's a very good first step.
Also, you could become a regular customer at a lot of small businesses, e.g. kiosks, run SUCCESSFULLY by immigrants, and once they know you, you could ask them how they did it, and what their most important warnings would be, to you. From them, you will learn other things in addition to the laws and regulations (which they will know, too), for example how necessary they think certain skills are, how they travel, what it involves to buy supplies, how the business involves their families and free-time, what their attitude is to their business, what they believe is emotionally, mentally and socially important to make it work.