meta tags
internal linking
external linking
proper navigation
proper keyword density
unique content

all are important for SEO.

Every On-Page seo technique is important for website to get good impression on search engine. But out of them Meta title and meta description tag is very important to tell customer about the site because it will be list on search engine.

meta tags , Heading tags , alt tag are most important in on-page seo

Best ON Page Optimization techniques are
1)title tag
2)meta description tag
3)meta keywords tag
4)canonical tag
5)alt tag
6)sitemap generator
7)google webmaster tools

On-page optimization includes Meta tags (meta title, description, keywords), URL analysis, keywords density, Heading tag optimization, Image alt tag, internal linking etc.

1. Page Title
2. Description
3. H1 Tag
4. Other H2,H3,H4 Tags
5. Keywords in the content
6. Other tags like image ALT tags

most important is meta title than meta description than others factors...