Presentation letter sample for travelling business?

Hello, I have started a travel agency, which offer services to the clients. The services we offer are international and domestic tickecting, visa assistance and processing and group packages (inbound and outbound) foreign exchange, etc.
I am looking for a good introduction letter of my agency, so that I can forward it to my new clients and companies.
So how to prepare a introduction letter, kindly help in drafting a letter to me
Thanking you,