Always choose high search rated but less competitive Keywords for your Onpage Optimization.In on page optimization you have to select some specific keywords who less competitive but have a large figure of search volume in Google adwords keywords tool.So lets what's important in On Page Optimization.
Page Title or Head Tag.Each page starts from the title of page as an most important element and description starts from here for both search engines and instant visitors for example if your page is about to selling auto spare parts then your title should be related to the topic of site some thing like buy auto spare parts.It will help search engines to track your site auto spare parts niche and visitors also have related impression.
Define Seo friendly Meta description.Although your meta description does not include as rank higher factor by any major search engine but meta description is an important place to bold the meanings of page title that occurs in visual snippet of the search results that when some one type same words in search box as in your meta description the search engine will show your page in top ten results.There for you have describe it using your most branding keywords in different meta sections.
Seo friendly Use of selected Keywords in Body text.Try to place your main keyword or keyphrase in very start of your posts or article that you are willing to write and use them for several times in whole post but remember never cross the limits to avoid from over optimization.For example if your post consist of one hundred words the keyword ratio would be 3 to 4 times.
Place your Targeted Keyword in Alt Image tags.Make related images or find them for your posts and use them for more describing your motos by taging them with your main keywords that will give you some extra space for extra use of keywords over riding the over optimization
Choose a Domain Name-Does your Keywords Trust for Search Engines.As Google's rules says that how much your site's briefings match or relevant with the word that typed in search box, and remember your all descriptions start from your domain name for example if you are selling bicycle then your site's name should be bicycle.com which most likely the exact match to your main keywords and for search engines it can describe your site in more better ways
Be sure to choose the rich and exact match keywords for your domain name.