If your site is new to search engine, then you start with good ON page optimization for the site and get indexed in search engines. After that you can start building some quality backlinks for your site that must be relevant to your site's theme. Initially you can go for the long tail keywords ones if you get your site for those keywords, then you can work for the keywords that are highly competitive.

Instead of practicing directory submission, article submission, and other SEO techniques, you can regularly update your site with good fresh content and start building the good hierarchy within your site. This will help you improving your site for the keywords.

You should be knowing that doing SEO for website is not as easy as it was previously. Specially Google has gone through many changes in SEO algorithm which has made SEO quite a difficult these days. So if you are not experienced in this, you will find it difficult to rank those keywords.

It will take some time in showing the result.You can also do forum postings and other off page tasks to increase your keywords ranking.

You can use SEO AND SMO technique.

hi guys need the assistance I have been posting directory, bookmarking, article and press release for a particular keyword but there is no changes in a google ranking kindly tell me how to improve my site