What is the key rules to improve your sales ,by competition ,relation sheep ,or quality product?

All that you have mentioned. My extra suggestion would be by establishing strong credibility by exihibiting honesty towards whatever you sell.

By effective communication and complete product knowledge. 

Don't put your products into competition...........make yourself different. Product Quality Makes you confident.........no matter what's the price. Give Respect and Get Respect..........every relationship based on this..........TC

All of above plus proper motivation

quality products do more of selling themselves before anything

Quality.

Relation ship.

competition.