How do you discourage somebody who hits on you at work?

Pray about it. Often God will take our prayers and resolve the situation without further input from us. If it does continue, simply let her know that she is disrespecting you and the result of the disrespect is that she is continually making it harder for you to even be friendly toward her. If she still doesn't respect you, take it to HR. However, you may want to start keeping a journal of events in case HR needs evidence.

I'm a flirty kind of guy and just about will flirt with any girl in the office specially those that likes receiving it. But there's always 1 or 2 who don't know me too well specially when they are newer employees. And here's a few that has been effective on me from those who preferred that I should not flirt with them:

1. Do not entertain it, If you are friendly with the person, continue being friendly but the moment the situation becomes flirtatious, move away, or even just ignore the comment or action.

2. Say "You embarrass me when you do/say such things, I am sorry, I really get uncomfortable when you do that". It sounds harsh but when you say it in a friendly way it's ok.

Those are the most common two things I';ve heard.

I would let her know that you are keeping a journal of her hits, and if she persists that you
will take to HR. If she scowls, etc., go directly to HR.

Tell her sometimes the things she says and does make you uncomfortable and you think it's inappropriate behavior for the work place. If she continues take it to HR.