1) First of all decide what kind of bike you are searching for. Eg, Racing bike, commuter bike or both. Select among the geared ones or gearless.
2) Do not trust the price money given on the websites. For price realated questions ask the Authorised center only.
3) Read users reviews on various web portals. Ask your friends about the bike you are looking for, if he owns it.
4) Take a test drive. Ask the dealer about the mileage, full functions and specifications.
5) Dont forget to buy a cover for your bike. The covers really keeps your bike protected from scratch, dusts etc.
6) Follow up all the instruction given by the company regarding the usage. Eg maximum riding speed, service period, oil to be used etc.
7) Always wear a Helmet while Riding.