The internet is the easiest way to find internship vacanies
Most of the internships I apply for are Fashion Journalism or PR related, so one of the main sites I use is Gorkana. Its super easy to navigate and you can narrow your search by discipline, location and salary - however if your going to intern please remember there's little to no chance of a salary! I found some good internships here as most of the major fashion publications use it, even Vogue.
Another good site for internships in all areas of fashion is Fashion Monitor. It doesn't often have many writing positions but does have a lot of pr internships as well as cool and sometimes random jobs like model bookers or account managers for fashion brands.
Another way you could try and bag an internship is to try and approach a person directly. This is easiest if the person has a blog or website as it should be fairly simple to get hold of them directly. Working for a blogger can mean you get a lot of hands on experience - at the very least your know you won't be stuck in the dreaded fashion cupboard all day - as chances are they won't have one! This is a slightly unorthodox method so be prepared for rejection, but like all vacancy applications if you approach the situation in a polite and professional manner you should get some joy eventually.
Good luck on your internship quests...
