Marching for a cause can be effective as well. If you can get a million people to march for a cause, this will do a few things.
First, it will show the country that the issue is an important one. People care and they will not take the status quo anymore.
Second, it will encourage the protestors, because they see solidarity. In other words, they are not alone. They know that many people agree with their cause. This will give the cause greater impetus.
Finally, it will make the government think and act.
I think two important issues today are: financial reform and political reform. Banks need to be made smaller, bonuses need to be cut, and politicans need to be more honest. For example, they should not be able to trade stocks with all the inside information they have. Also they need to be less partisan.