About 8 months ago i went vegan after being a vegetarian and there was a huge difference in my complexion! But then a few months ago I started having dairy here and there again and my face went crazy. Now I cut it back out but am stuck with getting rid of my acne and the scarring. I recommend cutting out dairy (of EVERYTHING that means no cheese, milk, milk products, yogurt etc) for a few months and seeing what happens. I know it works for a lot of people. There are a lot of alternatives to all these things, although some of the vegan options take some time getting used to (but now whenever i eat cheese it really grosses me out). Just give it a try for a few months and BE STRICT on yourself, because sometimes just the smallest bit of dairy can mess everything up. I know a girl that stopped consuming dairy for years and then started again and broke out in horrible cystic acne that took here even longer to get rid of. Everything is worth a shot, so give it up for a few months and if you see a difference then great! if not, then you can go back to your regular eating habits.
As for green tea, it is very good for you. I would recommend at least 3 cups a day. Hot is the best way to drink it with no added sugars or anything (you'll get rid of all the good stuff if you do this) you can drink it cold also, its just not as powerful. You can add a tad bit of honey, i know that doesn't completely make the green tea loose all its antioxidants and such and honey is really good for you but honey also loosing a lot of its great factors when added to hot drinks. So that kinda sucks for a green tea and honey drink but if you can't handle the taste of plain green tea had a teaspoon of honey. hope this helps! )