I am trying to book two tiny hotels in Switzerland which are asking for my credit card information by email. I'd prefer a more secure method of transferring the information. What have you done in this circumstance?

This was a while ago, but a small hotel in Nice once asked for my credit card by e-mail, and within 24 hours that credit card was used for hundreds of dollars in purchases at a photography store and a grocery store in Nice, so I called Visa and cancelled the card. But I wonder . . . could it have been random coincidence?

you could

a) split up the cc info into several emails.
b) make a pdf of the cc info, and password protect that file, and send the pw separately
c) call the hotel directly and give it over the phone. or
d) go ahead and send it, knowing that you are not responsible for any unauthorized purchases.

#c) Bingo! Whenever I've been asked to e-mail credit card or other confidential info . . . I simply pick up the phone and call it in. Easy. Why jump through hoops??

Call them

Done! Thanks.

They should be providing a secure way for you to pass that information without emailing or giving out the number over the phone. Do these hotels have their own website where you could make the reservation and put your credit card number in for guarantee purposes? They should be PCI compliant if they handle credit card payments. It could be if you call them, they enter the credit card number directly into their system without writing it down first, which would be fine.

Generally if me I just pick a different hotel , one I can either book online or that trusts me to pay on arrival.
I have yet to have a hotel planned that was a must deal breaker stay. So there are always other hotels.
For me limiting a fraud is more important to me then any single hotel.