Zotero uses Collections and Tags to organise libraries.
You can use the Sorting functionalities to sort according to your needs.
You can use Colored Tags to add a star in front of the title field in the library center pane (just use ⭐ as a tag and make it a Colored Tag) and then use The Tag Selector to filter by this tag.
If you want to get more functionalities with custom star ratings, you can try the
Zotero Tag plugin or the Zotero Special Tags column plugin.

If you feel that some specific functionalities are missing for your workflow, you can explain in details what you want to achieve and someone in the forums may give some suggestions how this can be done already, or may be implemented in the future developments of Zotero.

I understand that you want to order the collections in your library as they appear in the Collections Pane. You can use any kind of special character as the first character of the collection name to change its order (numbers, punctuation marks, emojis such as ⭐, Cyrillic letters, Greek letters, ...).

Also note that the developpers have mentioned that:

A proper collection search may happen at some point, but you can click within the collections pane, press + on the keyboard to expand all collections, and just start typing the collection name to focus it.

Collection tagging is not planned.

https://forums.zotero.org/discussion/comment/386702/#Comment_386702