Finding a reliable SEO consultant in Delhi does not necessarily have to be a tedious process as everything can easily be done through the internet itself. You can Google SEO services in India or to be more specific in Delhi so you can get access to websites of different SEO Services that can assist you with ranking on your local version of search engines.
The best way to proceed would be through word of mouth recommendation from someone who actually managed to rank a website regardless of what business they might be in. You would obviously get better and more reliable recommendation from people who might be in a different niche to yours or people or who may be from a different country as you would not be posing a threat to their own businesses.
Another way would be to seek recommendations from anonymous individuals that you can usually get in touch with online through forums that specialize in SEO as they could be recommending SEO Services that they may have successfully worked with before. The only thing would be to double check recommendations that you get and to verify any suggestions relating to SEO services in India, that you get so you can be sure of identifying the best SEO consultant in Delhi suitable for your business type.