I've made a pledge not use Styrofoam or bottled water.
Staying green while interviewing for a new job can be kind of tricky when interviewers are trying to be polite and offer you food or drink. So if you are green, think ahead on how you are going to react to have the proper interview etiquette
When I interviewed for my day job, my prospective supervisors and employers offered me bottled water. We were in a fancy conference room and I could see a little kitchen off to one side. I could see a sink and cupboards, so I told them that if they had tap water, I would prefer that to bottled water. But I didn't tell them I had taken a pledge not to drink bottled water. I didn't think my job interview would be the best time to bring that up.
Also when I'm interviewing and offered a cup a coffee, I will quickly scan the area to see if it will be served in a Styrofoam or a ceramic cup. If it is a Styrofoam cup I will politely decline, but I don't say why.
So, if you are environmentally minded, made a commitment to staying green and also job hunting, think ahead to what small curiosities might be made to you during an interview and practice how you will react. Remember to stay polite and keep a smile on your face.