My site is stuck at #3. I'm thinking of adding new posts to my site which is on WP. Suppose my keyword is "run fast". I've used this keyword in my content and have optimized it. If I add more posts then this post will move to another page from home page. How will it effect my SERP?
First, without seeing your on-page optimization it's almost impossible to guide you in regards to it. You might need to just work more on your off-page optimization (link building). I'd try build more relevant backlinks using as anchor the primary keyword you're trying to rank #1 for.
It could potentially effect your SERP. What I have done is I have one article that really does convert well for me. It has really good content and I want it to stay on the front page. What I have done is "stickied" that post in the Wordpress admin. This way it is always the first post read by website visitors. I continue to add fresh content because Google appreciates that and it has worked well for me. So long as the content you are adding contains content related to "run fast" then you shouldn't see a drop.
Thanks. Very useful reply. How have made the first page stickied? I need to do the same. My site is acca past papers
I totally agree with "PHPGator". He has given a really good trick, but for this trick to be successful there is a need of constant content updation. You can also try to promote your article on Social media sites like Facebook and Google plus.