What will prevent a guy from hitting on you?

It happens to everyone- man or a woman to attract the attention of someone they don't want to. It can happen at work, in the gym, in the favorite caffee, bar, restaurant, in the public transport. What are the right signals that should be sent in such a situation to make him realize you're not interested?

- Don't wear too sexy clothes when you expect to meet him. Especially if you work close to him.
- When you seem him, pretend to be very busy with something- talking on the hone, texing a message, looking for something in your purse.
-Don't keep eye contacts with them.
-When they ask you something, avoid making a conversation. Keep your answers short to 'yes' and 'no' and ask them if they need anything else. Make an excuse and leave as soon as possible.
- Never speak about you, don't tell him the area you live, if you are having a bad day, ect. He is looking for a reason to make a conversation and to get closer, don't give him any.
- Wear a heart shaped jewel, that will clearly show that you are not single
- In cease you have to contact him, for example if you have a common work to do, never give him your personal number. Ask for his number/e-mail and don't give him a chance to bother you.
- If non of above works, just tell them you have a boyfriend and you're not interested in him.