Hi, I set up as an independent (sole trader) in Geneva a couple of months ago. I was dreading going there but, just like Aussiegirl said, it was very straightforward- just one form, the woman made a phone call to some federal office in Bern, gave me a bill for 190chf and a few sheets of information and that was it. I visited a website that she told me about a few days later and could print the company documents directly from there, official copies were optional for a small charge.
One thing I was told and no-one else here has mentioned is that you will receive a ridiculous amount of mail with bills, offers, association memberships etc. NONE OF THIS IS MANDATORY!! and I think the best place for most of it would be the paper recycling bin.
I have, however, now received a reminder from SUVA which I think is a declaration of how much I think I will make in a year so I can pay AVS and other stoppages. Any info on this would be most welcome if anyone out there knows, it's high on my to-do list and looks pretty official.
Just for info I'm a Brit with a C permit but the process should be the same as long as you have a valid permit.
Also, if you want to register a SARL (Ltd company) there is the small matter of putting aside 20,000chf which is some kind of deposit in case you go bankrupt. For an SA I think the figure was 100K! As a sole trader I am the company and we are one as far as the law is concerned- if it owes someone money then so do I, that is something that should be understood if you register as a sole trader.
Good luck if you decide to start something up yourself and don't be scared, everybody has been surprisingly helpful for me.