Despite all protests to the contrary and menus marked service compris, the Swiss do tip at restaurants, but it's not done as a percentage. Instead, they give quantities anywhere from the change from the nearest franc to 10 SF or more for a world-class meal that has been exquisitely served.
If, in a café, the server settles the bill at the table, fishing the change from her leather purse, give her the change on the spot—or calculate the total, including tip, and tell her the full sum before she counts it onto the tabletop. If you need to take more time to calculate, leave it on the table, though this isn't common practice in outdoor cafés. If you're paying for a meal with a credit card, try to tip with cash instead of filling in the tip slot on the slip: not all managers are good about doling out the servers' tips in cash. Bartenders are also tipped along these lines.
Tipping porters and doormen is easier: 2 SF per bag is adequate in good hotels, 1 SF per trip in humbler lodgings (unless you travel heavy). To tip other hotel personnel, you can leave an appropriate amount with the concierge or, for cleaning staff, with a note of thanks in your room. Porter service fees at Geneva and Zürich airports depend on the distance covered and number of bags, but average out at around 5 SF per bag. Tip taxi drivers the change or an extra couple of francs, depending on the length of the drive and whether they've helped with your bags.