Edit: Oh yeah, I made neither of these images, nor did I check precisely which corps are in the flag. I did however use my sick GNU Image Manipulation Program skills™ to add and scale them together. I did it for the bit.
Well if i havent seen most of them being boycott targets for their involvement with Israels crimes.
As for how to organize boycotts i recommend to check out the website of BDS bdsmovement.net/ it has tips how to organize local boycotts and there is campaigns for many of these companies already.
The most important is to do targeted boycotts. Focus on a few brands/companies and apply maximum pressure, while talking about it to get more people to join. Make them know that their drop in sales is a result of their complicity.