Rule number 1. Do not disappoint your Potential Customer.
Rule number 2. Do not make an impression that make them turned of. eg. Body Language, E×ρréššion.
Rule number 3. Know your items. The better your knowledge, the more you can present them.
Rule number 4. Know to be Polite, Honest and Patient.
Rule number 5. Have the approachable vibe so potential customer won't turn away. 'coz you know filipinos is shy. lol
Rule number 6. Have the skill to observe the potential customers action for When and Where you should act so that they won't be intimidated by your actions.
This is more of a tip than rule.. Anyways good luck!