By going cruelty-free and boycotting brands that test on animals, you’re speaking their language and letting them know that their unethical practices are unacceptable.
First you need to understand what cruelty-free means and why it is important. Animal testing does not only cause suffering to millions of animals, it is also very inefficient science. The only reason why animal testing exists is because animal tests are cheaper than non-animal alternatives, even though they’re actually less accurate.
A “cruelty-free” brand is a brand that doesn’t test on animals. A “vegan” brand is a brand that doesn’t use animal-derived ingredients.
Th term cruelty-free is not regulated, so it is good to research about brands, as some label themselves as such, even though in some cases they do test on animals.
Second, research the brands which do not test on animals (or are even vegan) and which do.
Third, keep buying only from these brands and spread the word (always in a kind way).
two links to help you get started:
https://www.crueltyfreekitty.com/cruelty-free-101/how-to-go-cruelty-free/