First of all 650 is not so bad but your score is very skewed. Secondly, you are in a highly represented group of IIM. Thirdly, your age is higher and you have to work hard to sell yourself to the school.
I had gone through similar situation and my approach was different. First, you need to identify what you truly want to achive from the programme. I am not asking for your essay to schools, but your true reason ... hope you understand what I mean.
Once you know why then you will be able to identify the right school for yourself. You are not a 4+ years WE guy who can try out few careers and hence can afford to blindly join ANY branded school. You need to be very selective about your school as your stake is much higher.
A very simple fact that many failed to understand is
NOT ALL SCHOOLS ARE FOR EVERYONE. So don't ever blindly follow the rankings!! Choose your school rationally.
IMD is one of the best school but average age is 29 and they are very specific about their average age and quite reluctant to consider over age students.
Cambridge is very selective and you have nothing extraordinary to showcase.
INSEAD, Oxford, although not impossible but will be tough with a 650, specially for IIM without any truly exceptional achievements.
HK and NUS has fair chance but you need to understand their strength and weaknesses and need to findout how closely they fit into your personal objective.
Finally, you are a bit late for 2013 intake as most of the schools finished their first round and second round also started for many school.
Best of luck