Number 1 - Banks
Ideally keep as little money in the bank as possible. Choose smaller banks over larger ones. Use credit cards as little as possible. Banks have funded most of the wars of the last 200 years. International banks funded Hitler, without them World War II probably would not have happened, or at least would have been over much sooner. Update: UK Banks funding cluster-bomb industry.
"When a government is dependent upon bankers for money, they and not the leaders of the government control the situation, since the hand that gives is above the hand that takes... Money has no motherland; financiers are without patriotism and without decency; their sole object is gain." - Napoleon Bonaparte, 1815
Number 2 - The Military
Boycott the military in all its forms and anything to do with the military. But somebody needs to fight the bad guys right? For one thing, our leaders are the bad guys and giving them a powerful military is suicide. For another thing, our leaders (more accurately, our leaders bosses) created and supported all the "bad guys" of the last 100 years at least. Support of war in the media is the dirtiest propaganda there is, don't fall for it. War is a racket.
Number 3 - Global Corporations
A simple rule of thumb: the bigger the corporation, the greater the evil. As much as you can choose smaller companies over larger companies. From Exxon to Monsanto, big corporations are working 24x7 to destroy your quality of life.
Number 4 - The Mainstream Media
The mainstream media have perfected the art of propaganda: most of the population still does not see it as such. Reading books like Manufacturing Consent or Asper Nation will open your eyes. Support independent media and boycott the mainstream media.
Number 5 - Join Up
The truth is the problems of the world will not get solved without your involvement. Like a union, the world's managers (the super rich) meet regularly (but in private of course) to discuss how to run things. Their goals are to further enrich themselves, just as they have been doing for many years. No one bitches more about unions than the rich. The rich have unionized, they just having fancy names for it, like "summit" and "organization".
Is it time you started taking care of your own? Don't bother sending letters to politicians, they don't care about you (click here and scroll down to "Who Owns You"). Look for causes you believe in and get involved. Join groups like TheZeitgeistMovement.com, Green Peace, etc. Forget groups like the World Wildlife Fund - they fall to recognize they are losing the battle and are too closely tied to the corrupt elite.
All that is necessary for evil to triumph is for good people to do nothing.