I am well versed of responsive design and development. I always take mobile first approach and try to minimize loading time. As per google SERP site should be mobile friendly. That's why it is getting more importance now days. Responsive website development includes... 1) Mobile UI/UX observation 2) Page speed testing 3) All Popular device friendly 4) Image optimization 5) Touch icons creation 6) Proper meta tags implementation and many more. Every project has its own requirement so communication can clear the requirement, and I can say more about responsive web development.