Hi,
The best way to find out a reliable registrar is by searching their reputation online. Many registrars in India, that I heard, might create you a problem when you want to do something with your domain name, for example, changing the DNS. Instead of wasting your precise time in searching for someone through this method, go for a famous and reliable registrar.
In this case too, only few reliable registrars are available. The rates between them and godaddy (the best registrar, IMO) is not huge. In my case, I always prefer to register my domain through google apps + godaddy (Yes, there is a tie-up between godaddy and google apps in this regard) that gives a lot of advantages like privacy (your contact details won't be shown when somebody tries whois information).
Hope this helps.
Kind Regards,
Pothi.