Most Common SEO Mistakes

Website is entirely created with Flash without an HTML alternative
Although websites created with Flash can be very pretty and attractive, search engines cannot crawl them. Since they cannot index your content, you will not rank for the keywords you would like to. Therefore, you should create an HTML alternative of your Flash website and provide your visitors with the option to choose one of them. By doing this you will increase the usability of your website and improve the way search engines index it.

Targeting the wrong keywords
You should carefully choose the keywords, which you want to compete for. For example, if you are making a website for your local American football team where you only feature the players and their results, you should not aim for a keyword like “soccer” as you don’t really care where you rank on the word “soccer,” even if you mention it anywhere on site.

Missing "alt" tags in the code for your images
Unfortunately, search engines cannot scan what is shown on an image. They cannot distinguish a photo of a flower from a photo of a truck. The only way they receive information about an image is through its file name, its title and "alt" tag. Make sure you enter relevant title and alt tags for each one of the images on your website. You should give them meaningful names; avoid using image1.jpg, image2.jpg, etc. By doing this, search engines will receive the information they need for your images. In addition, they will be included in the search results when someone searches for a photo in Google for example.

Duplicate Meta tags
This is a common mistake among web designers. Meta tags should be unique and meaningful for each separate page. If they are the same, search engines consider them as duplicate content and rank you lower in their search result pages. Or, if you target the same set of keywords with two different pages, your pages will be fighting between each other for a position in results on the same keyword thus devaluating each other’s worth.

Failing to create a content hierarchy
Many web designers underestimate the power of a well-structured website. Search engines rank higher websites with well-organized content. You should use heading tags (h1, h2, h3) to organize your text. This will improve the readability of your content and the way search engines index it.

Quality of content is king, we cannot cheat search engine with worthless content.

Thanks for sharing the content, really found it interesting and duplicate content is the biggest issue in SEO. If you are not posting a fresh content to website then it cause huge harm to your website. web content writing services

I did these mistake when I was new. :) in my 1st project I was just like mistake man