There are plenty of ways to raise awareness of an issue. Writing is a great way to convey ideas. Writing a column for a newspaper or writing a blog post can help spread your ideas. Making a YouTube video. Talking about the issues with friends, family, and total strangers. Talking on FB or here and other online forums. Getting messages back and forth and having them spread like wildfire is very easy in contemporary times.
There are plenty of legal ways to enact change. You yourself can run for office. You can get involved in party politics. Don't ignore the parties, because they control the process. You have to enact change from within. Vote in primaries and elections. Address your elected officials at town hall meetings, council meetings, etc. Go to speeches and party events, not to protest but to get your message to the office holder / candidate.
Yelling and screaming in the street is a complete break down of the process. It may have been necessary due to technology limitations in times past, but it is no longer.
(This post is obviously inspired by the OWS. However, this thread is meant to discuss the tactic of protesting and not the issues of any particular protest.)