My site is about a month old now. My main keyword ranks in the top 30 already on bing and yahoo. I have seen it in the top 100 on Google but that last week now it's not ranking in the top 500+. I have no message in webmaster or nothing and did no major changes on my site. Seems all my post are ranking but my homepage and main keyword is just not ranking no more and can't figure it out. Can someone please give me some suggestion why Blend Your Smoothies isnt ranking at all for it keyword? I have about a 1.3% keyword density with great content. No really sure what the problem is here... http://www.blendyoursmoothies.com is my site and main keyword is Best Smoothie Blender
Have you check on it again using a different device? This happened to me too but the other way around, from no. 100 to no. 2! Yeah crazy it is, but that was just for a moment. I refresh and check on it again and *voila* back to its original position. Good thing though I was able to have a screenshot on it ahaha
First article I see: "Smoothies are one of the most refreshing and healthiest drinks on the planet. To make the best smoothie possible you will need the best smoothie blender. Having the one of the best blenders will always get the job done right the first time. It’s important when choosing the best blender for smoothies this guide should help you make the best choice." Do you call this great content and low keyword density? All I see is are the words Smoothies and Blender and their variations stuffed in every article. And I looked a few more too? Seems to me you were hit by the Panda penalty and you should definitely look into changing your texts to best serve your visitors and not just randomly put keywords.
SERP is NOT only based on on-page SEO. Something your website is currently lagging is trust/authority in the eyes of Google. A website that is "only" 1 month old can't have decent ranks yet on keywords that have some competition. Yes, you can get a decent rank but you might drop 20 / 30 ranks within days. Most people say it takes 3 / 4 months before your rank will get a bit stable, after that you can start analysing and improve the weak spots.