How do I find the 10th school year that suits me?

First ask yourself what you hope to get out of this 10th school year and choose the school that can fulfill your hopes. For example:

If you are planning to work in the hotel or travel industry later on, it makes sense to combine a commercial vocational preparation course with a language course.
If you want to learn a skilled trade, choose a general apprenticeship where you will learn German and math really well so that you don't have any disadvantages later on with customers and business partners.
If you struggle with things like punctuality or getting along with other people, choose a school that has coaches and teachers who impress you.

If you are still at school, your career choice teacher or careers advisor can help you decide.

If you are already out of school and need to register independently, use the following options:

Check with the careers information center in your canton of residence to find out what is offered there as a 10th school year.
Enter "10th school year" in the course search at www.ausbildung-weiterbildung.ch and take a look at the offers.
Most providers hold information days where you can take a look at the school. Take advantage of these info days. Maybe you can talk to people there who are currently in their 10th year.
If you like an offer but are still unsure, ask the school if you can try it out for a day.