Hi Shirish, please do not use Director as designation in your visiting cards or in your communications as well. Director designation is used for company form of entity. You can use as Partner if you are a partner of the firm. But for employee of your firm you can designated them with Executive, Sr. Executive, Officer, Sr. Officer, Manager, Sr. Manager, Vice President - Marketing, Vice President - Finance, Vice President - HR.
Also to very senior employee you may give designation as CEO.
However get your firm registered with ROF (Registrar of Firms) and along with your firm name write registered.
Hope I have tried to clear your doubts, do let us know if you need any further clarifications.
Regards,
Mukesh TANK
9967590445