Best way if some serious (and habitual) stalker is there is to convey it to the parents, and give police complaints.
For people who work up to odd hours or have to travel alone in not so familiar areas, it will be better to have a pre planned safe exit methods or routes. Karate or chilli may be tried as a last resort, failure in any of this may be disastrous at close quarters. Best is to bail out of the situation as early as possible. It is always good to listen to inner consciousness, (the sixth sense) and get out of the problematic areas. If you are a little vigilant thier might be no scope for surprises.
It is always better to avoid taking problematic routes. Nights in most cities are not safe even for able bodied men, and theft is common. So it is better to avoid overconfidence, and reduce i will take the world head on attitude, in dangerous places.
I dont think assaults are result of dressing style. I think the assualts are driven by attack on a weak person by a strong one or group. So better keep away from being week.