What mistakes you should avoid while optimizing the website?

[virendra]

The main mistakes that should be avoided are filling keywords in webpage, employing identical anchor text for link building, keyword stuffing, getting low quality backlinks etc.

[Anny87]

I guess keyword stuffing are the useless stuff that should be avoided by any web site analyzer. And rest are also mandatory which you have share to create a good web site.

[oliviagrant]

Avoid to build low quality backlink and spam link and also avoid use of duplicate content.

[shoponics]

i also agree with you and i believe you just want optimize your website organic way else you can't get good position in google and in this google say" you just optimise your website for user not for google"