Yes. I'm a protestant and I doth protest all the time. I have protested with signs at puppy stores that sell puppies from mills. I attend "fur-free friday protests" because I am against the fur industry. I had a couple furs and donated them to use in protests.
I protest with my wallet. I protest with letters and phone calls. I protest with leafletting. I protested the Canadian Seal Hunt at Red Lobster because they buy their seafood from Canada. They still do but Whole Foods doesn't.
More often than not, the outcome 'eventually' had the desired effect.
More examples: I won't go to Sea World because of their policy on keeping these Orca Whales (Highly intelligent dolphins) in captivity. I believe that someday they will change that policy because of public pressure. I also will never go to the circus that uses animals because I believe they are abused and I don't support animal cruelty. Someday I think they will stop.
I am protesting the fees the banks are charging and I have closed my accounts at BofA and Wells Fargo. I took my business elsewhere.
I protest all the time with my body, wallet, written word and spoken word.
It's the only way.