Mistakes You've Made that Affected Your SERPs

I open this topic with the hope that here will be a whole list of mistakes that people made, and after that they noticed that their SERPS had dropped.

I'll start with one personal mistake.

One day I've added a new h1 with my targeted keyword, and this was the 2nd h1 on that page, and after a while I've lost my rankings. I think that google thought that I might be a spammer. After I deleted that h1 my rankings came back to normal.

Now I wait your experiences ...

 

When I was youger, so much younger than today . . . .
. . . I did the old invisable text rubbish on a site I designed for a friend.

I couldn't understand why the site didn't improve, infact it went backwards after 2 months. I removed the offending text and guess whay? Yup the site shot up the rankings.

 

Biggest mistake we made was when migrating a site from ASP to .NET. We had 1000's of high PR pages that ranked well and ensured page names were the same (IE still had page.asp rather than page.aspx) but with one minor (major actually) over sight.

We didn't consider case sensitivity. The old site had pages such as products-page-1.asp and the new site had Products-Page-1.asp - as far as google is concerned, they're totally different pages. We lose PR on 1000's of pages and virtually the whole site went into supp.

Yes it was a silly mistake but easily made when using IIS, etc.

 

I got someone on these forums to submit one of my sites to a bunch of directories. You know the "submit to 200 directories for $10" threads. Within a few weeks, the site dropped from page 1 results to page 5 in Google. It took about 5 months for me to get the site back to page 1. It wasn't affected in MSN and Yahoo search.

 

building backlinks to fast will also hurt your serp.

this is a mistake that i made

 

Adding a lot of broken links will drop you down. I utilized a lot of user supplied data to generate pages and friendly URLs like this page: Pediatrician Salary. I rolled it out after checking a bunch of links. Google ate it up and gave me a lot of high rank, long tail links but they disappeared one day.

After researching I found that special characters (like commas, periods, slashes, etc) in some of the user data left me with 5 to 10% broken links. I fixed the problem and about a week later all the links and traffic came back.

 

I just did something similar.

Made an update to a site and was building the sitemap. copy and past a bunch of paths then typed in the file name. Had a character missing in the path... oops

60% of the site showed 404 in webmaster tools, fixed the error and about a month later Goolge had erased all the 404's.

Main keyword went from 3rd to 28th in results and lost most other keywords. After the recent update its back to normal.