A protest is a voice, hopefully of reason.
What is the problem that motivates the protest? What is the aim of the protest? What action would the protest hope for? What reaction should be avoided?
Therefore a protest, in essence, is like selling, in that we hope our protest leads to results. What are we selling and who are we selling to?
When we are selling something as large as an ideology and we want change, there are two options: force and negotiations. Force leads to violence, and we don’t want that. So we are left to negotiate.
Rule No. 1 in negotiations: Never send an angry person to negotiate.
Therefore, this is an old hippie’s words of advice to a protester: Make the protest about your cause, not the anger you feel. Expressing anger may feel good, but it will not help your cause.