Is there a way to protect myself from my credit card being charge during a free trial period.

I always want to sign up for free trials offered by companies but I have always been reluctant to sign up when they request credit card info. to qualify for the free trial as I am concerned of being scammed.
I have heard of people being charged for BS charges even though they canceled before the trial period ended.
Is there a way to avoid being ripped-off and in avoiding unscrupulous companies.