In On-Page the most important factor is the Title of the page. If the title of the page is not effective, it will not help to get traffic neither to rank in Google SERPs.
Do proper onpage step by step as :
1.Title(not more than 64 characters)
2.Description(not more than 164 characters)
3.URL structure
4.Proper SEO friendly content
5.use of proper heading tags
Create appropriate website tile with keyword prominence and proximity.
Make URL structure SEO friendly
Choose competitive keywords
You can also hire a professional for on page seo , like BarryinSiam on SEOclerks.