How bad is it? If its just kinda bad but not you need medication bad the 1st thing I'd suggest is drink lots and lots of water to the point were that's all your drinking and you pee its crystal clear almost. Next with one of those bottle of water take Apple cider vinegar in it everyday ( I believe its a teaspoon to per 20oz, but look it up) or you can get apple cider vinegar pills which don't work as well but still work good.
Next I recommend using this brand of black soap on your skin everyday or every other day.
After you shower make sure to moisturize your skin with some from of lotion, I use jergens shea butter and it works wonders, you want to use a lotion with shea butter thats key.
Finally invest in some of these and use one everyday either in the morning or before bed.
If you drink alot of cold drinks or sugary drinks cut back on them heavily, you dont have to stop but a coke should be a once MAYBE twice a week thing, you really wont have the space for them anyway once you start drinking water like you should.