Hi

Can it go to fast, i have a high density keyword and it was not in the google top100. Then i started seo and in less then one week i had it on #18, today it droped till # 42.
Could this be a tempory drop becourse it ranked to fast, so google will set it back for a view weeks?

Google Dance

Code:

In search engine optimization (SEO),  Google Dance is an out-dated slang term used to describe the period of  time in which Google used to rebuild its rankings, and as a result of  this rebuilding, rankings of Web sites on Google's SERP may fluctuate in  order during a several day period. The "Google Dance" would happen  anywhere up to 36 times per year, however in 2003 Google begun updating  its index on a weekly basis, which all but eliminated the Google Dance.

It is know as the googla dance, follow the moves

It is normal but it doesn't mean you will get back to #18. You may get lower or higher.

Yeah it's dancing. When it is dancing between positions like #18 and #100 it is a good indication you will get decently ranked. Just keep on building links (not too many in my opinion) and you will see your website get a more stable ranking soon. Took me about a month of dancing so be prepared :P

keep adding content and building links slowly but consistently. make it look as natural as you can. don't forget the social signals

Use High quality Content and Slow LinkBuilding.

I've been linkbuilding with Magic - splits it up into daily tasks, really works well for me because I tend to rush everything all at once and then do nothing for weeks,
I had a site jump in 4 days from page 5 to page 2, I expected it to plummet out of the top 100, but instead it jumped up to page 1, then dipped back onto page 2 on and off for a few days, but now it's number 5 and staying there strong, so fingers crossed!
Good luck, and I hope it sticks for you!