One of the things I have noticed with many of my clients is that they seem to be spending a lot on Health insurance premiums. Although Health insurance premiums can be deducted from taxable income, there is a limit, and it is not very high. Most premiums are above the limit, even with a CHF 2500 deductible.
My advice generally is that, unless you have annual medical bills above CHF 1900, then always take the CHF 2500 franchise. Even if you have unexpected medical bills here in Switzerland, your extra cost is capped at CHF 600, compared to what it would have been on the CHF 300 franchise.
With a higher franchise, you have to pay your invoices yourself, but your premiums are much lower. Plus health costs not covered by your health insurance can be deducted from your taxable income ( subject to them being 5% or more of your taxable income).
PoorSwiss has written a comprehensive article all about health insurance. He also includes a comparison site for you to use that he recommends. I recommend you read the article to learn all you need to know and more.
You can change basic insurance every year, but need to do this by the end of November for the following year. Supplementary insurance is a bit trickier, and the PoorSwiss article explains why. Personally in all the years of living here, we have always had the highest franchise, and the basic supplementary.
The PoorSwiss article can be found here.