If your competitors are getting more backlinks then you are, they outrank you and your rankings drop.
Rankings won't drop because you have some incorrect information on your website or some false keyword density.
First you need to start getting backlinks, everyday get around 15-30. You can get more than that but the important thing is you get same number of links everyday. A 100 everyday will be difficult while 15-30 is realistic.
The concept behind it.
Getting backlinks regularly like that means something important to the search engines. It means your website is very good, since everyday people are linking to it. That is what search engines think when they see new backlinks everyday.
So it's easy. 15-30 is not that big and with certain automated software you can get 50, 100 or more daily.
If you are going to get backlinks create a link directory on your website. A one page links page is not a well created directory. It must contain categories and subcategories and link from the homepage.
You can invest in some scripts that that creates such directories, there are many of them.
OutBound Links means links pointing to another website from your own. In simple terms linking to another website is like giving them some of your pagerank, they get rewarded and you do not want to reward your competitors or any other website.
You link to other websites on your links page and if they do not link back you can and should remove their link from your website. That also makes a difference in your rankings. So make sure that when you do link exchanges you keep a record of where your link partner placed your link. Then check to see every now and then if they still link back to you.
There are scripts and software to help you do that automatically. If link exchange partners are using nofollow tags in the link pages you should also remove their links. There are plugins to allow you to quickly see if links are using the nofollow tags.
When doing SEO it is a good idea to focus on one few keywords. Find some 3 or 4 and focus on getting backlinks, changing the anchor text in the backlinks using all keywords. So it's like optimizing your homepage for 3 or 4 keywords only. A great start to get some traffic and money. Then you can optimize some other pages for some other keywords, or the same page for new keywords. You also become good at SEO and you get some experience.
When creating meta tags make sure your other site pages have different meta tags, not identical.
So the very important things are the number and quality of backlinks you have. Give the search engines what they need in order to reward you with high rankings.
