Get experience by working in a travel agency and travelling yourself. You need to build relationships with hotel chains and make connections to get clients. Goodwill and relationships are crucial in this business.
Recruit good staff
Recruit trained staff who are well travelled and have good communication skills, because most Indian customers still prefer to buy from a person than online.
Get IATA (International Air Transport Association) accredited if you want access to airline seating reservations (via global distribution systems such as say Amadeus and Galileo) and to have a more credible brand.
Register your business
Register with the government of India tourism office so that your company is published in their brochures. Get a 'shops and establishments' licence and of course, register with the registrar of companies.
Get funds in place
Sort out your working capital needs: You will probably need at least Rs 50 lakh because you often have to buy tickets on credit. Also, airlines expect a guarantee of money in your bank account to allow you to ticket for them. You also need a lot of money for marketing purposes and companies often pay late.
Market your company
Plan your marketing strategy: Market the company via newspaper advertisements, and create an online portal too. The latter is vital to build a visible brand.
Do something no one else is doing, for example by focussing on corporate or singles-only holidays.