Green tea is great. I drink it three times a day after every meal (it can cause acid reflux if you drink it on empty stomach). Probably any loose tea (not in tea bags) will work but I have been drinking Gyokuro (probably the most expensive but I buy Chinese, which is cheaper) and Thai Nguyen (Vietnamese, cheap but good quality). I take a table spoon per cup, let it steep in 80 °C water for 20 minutes. Put tea in and let it cool in a teapot, no need to keep it on a stove to keep it at 80 °C. The taste will be bitter but once you get used to it, it is actually very pleasing. If the bitterness is unbearable either the temperature was too high or the tea is bad quality (or maybe you just need to get used to it). Although the tea helps greatly I'd like to note that only after removing gluten from my diet my acne disappeared altogether.