How do you build and maintain a relationship with co-workers, key managers and customers?

Thanksfor invitation,

through 

1- respect.

2- coronation.

3- appreciation.

4- Honest.

5- Truthfulness.

Thanks for invitation. This is a very important question

To build and maintain relation with different stakeholders and group of people is must to survive in this globalized world.

1. To build/maintain relationship with co-workers, talk to them freely, discuss important/relevant issues and seek their opinion/support as necessary and try to have informal get together in office canteen during lunch or tea-break.
2. To build /maintain relationship with Key Managers, try to meet them in very short informal discussion once in a month, promptly reply to their e-mail and queries, seek their opinion in relevant cases and invite in formal dinner or lunch  appropriately.
3. To build /maintain relationship with customers, follow best customer service approach, support them with after sales service promptly, share info about new products, and invite  the important customers during new product launch. 

Performing tasks on the completeness and non-interference in other tasks and good behavior and good word and help others

Thanks 

I have to be professional with all you mentioned to maitain the relationship with them