My site is only 3 days to be 6 months old.

This website is unique, that is there is no competitor to this type site in India, providing comparison of payment gateways in India, besides the payment gateways companies itself.

I've optimized it for key word : "payment gateway"

I've changed the url's twice, latest being 3 months back, in which case Google Webmaster gave plently of 404's. I corrected the useful 404's and left meaningless ones as it is.

What is the reason it's not ranking well for payment gateways? Even site with single page about "Payment gateways" seem to be ranking better than this.

Is it does to: 1) Lot of outbound links to in-context companies and information 2) 404's as reported in Google Webmaster

My another site is successfully getting 1500 unique visitors daily and is up in Google ranking. I don't know why it is not!