I am working on Internet marketing for one of the Website designing & development company in India which is located in Mumbai. So the website is performing quite well in local search places or up to state level in SERPs. But not with all major locations in my country, so my question is what are the best ways I have to stay on top of the SERPs.
Rajesh, if you are looking to outrank others in SERPs in Google, then you will need to have physical presences in other metros. Add those addresses to your Google Local (they will even send you a card via snail mail to that address for address verification).
Once you have verified your address for all the major metros, you need to start pushing your fans for reviews across all these locations.
You might even wan't to get listed in the location specific services (although I cannot really vouch for any other service except Just Dial).