Best part of SEO is on-page optimization.
Because, content must be value to customer. Google look at that point first! Other factors are addition to it: keyword selection, keyword density, internal link, keyword in tag and important positions...
Since, substance must be esteem to client. Google take a gander by then first! Different components are expansion to it: watchword choice, catchphrase thickness, interior connection, catchphrase in tag and critical positions.