Please look for the following points while selecting policy:
1. Some policies come with caps on billing on several aspect eg room rent etc. Look for a policy without such caps.
2. Look for a company who has their own TPA.
3. look for a policy where you can increase the sum assured when you want to. you may now opt for a cover of 3L but you should be able to increase cover to say 10L if you want to.
4. most difficult of all. Go for a company with good claim settlement ratio.
HTH