On page seo need to be done … but the difference is made by the off page seo: how many backlinks you have etc.
This implies some work … but once you have it done you are just cashing money.
I would suggest working in promoting your site as wordpress is quite well seen ( as it comes ) by search engines.
on page seo is very important but if you cannot put your keyword in h1 tag don’t worry move off page seo and choose best niche web directory then submit your website there and write a good article and submit it at least 50 articles sites and also can do social bookmarking.
In on page factor - make sure to build good internal link. Every page must be link back to your home page. Apart from this consider on some off page factors such as building quality backlinks to your blog.