Tags are used to describe your icons. They are essential for the system to work since the search algorithm is based on finding icons that have tags matching the search query. You should describe all of your icons with as many relevant tags as possible.
Number of tags
It's tempting to add a lot of tags to make sure the icons are showing up on many different search terms. However, to avoid spamming, we give icons with too many tags a penalty. You should try to keep the number of tags around a maximum of five to seven. Keep in mind that if you add more than seven tags the icon will get a lower rank.
The bad tags
When tagging icons, you should avoid what we call non-descriptive tags. All non-descriptive tags will be flagged and colored orange. These are tags that do not directly describe the motif of the icons. In other words, do not use tags that do not describe what the icon represents.
Avoid the black list of generic tags
Unless your icon actually represents one of these terms, you should avoid these non-descriptive tags:
We will delete or block if designer uses offensive or blacklist tags
Sample for the good tags