It depends upon wheather ur buying new property or old, if it is old  flat then u should ask for chain of  original aggrements, current light bill, Tax recipts, society share certificate, Noc from society,Title clearance certificate, also get valuation of the property from valuer he will tell you the exact market price & other details related to the property.

if the property is new you should ask for land records current  7/12  if not 7/12 then NA certificate , other important things like survey no of land hiss no of land,  city servey no if the land comes under Muncipal corporation , & wheather developer has  rights for construction & proper permission from Building department along with other departments, ask the builder for  the approved plan of building check carefully if the plan is original it will have stamp of muncipal corporation with exact drawing number that you can cross check  with muncipal corporation also check the above mentioned things which i have given for old property there are many more things that needs to be taken care of , in aggrement with builder before investing for details contact me or meet me @ 9820871963