My site rank is not consistent. Once it at first page , then for the next week it is not found in top 100 position. Again two/ three weeks later it ranked automatically without any work. Why this is happening?

[coldfireinc]

Here's the following are available in my site:

robot.txt file is included

sitemap available

Natural link building going on. in a week total 100 links  we are creating. 30 social bookmarks, 30 directory submission, 20 blog comments, 20 forum links

All the blog and forum links are from relevant sources.

Please help me ..

[Personnel_Concept]

It happens sometime. One reason might be the changing competition of the keywords that your site is optimised for. I have noticed the fluctuations in the some of the sites even though we are not doing anything with them!

Google's crawling rate has becomes faster lately and resulting in more fluctuations in results.

All you can do is keep increasing the authority for your site by quality content building and link building. So that Google trust your site and rank it on first page consistently. Also check if you got any spam links and try to remove them.

[coldfireinc]

Thanks Vikas_Rana for your helpful answer. Another thing to know. Should I continue with this link building strategy or should I change the strategy?