Actually I would not call my way of using ratings and colors to be a system. Maybe a habit I tend not to change unless needed.
Most of my time I shoot event like stuff. I ingest and use no color for images not having looked at. Upon checking out an image I decide if it is good enough for a website display without editing (save as from PM) or it need some editing in PS or LR, or it is not worth for publication in any form.
When I check an image I add crop and a color class usually one of these:
Red image OK, not much edit needed
Green edit needed
Purple additional info sheets photographed like names list or maybe other interresting stuff
Blue info helping identification as nametags, ID numbers, etc
Trash image rejected
Orange and Cyan usually mark images I select one or another paper to send. Usually I don't display in an event gallery images sent to any of the papers.
Star ratings are used by me for different groupings of images for example parts of the events, categories or so.
Tagging usually means if an image has been completed and uploaded so I can filter it out (showing untagged ones only).
For different kinds of favorite images I like I prefer to use a keyword that is not that often interacted by my workflow as color classes. For example fun images have a fun keyword, exceptional images get a select keyword.
For simple press assignments where I don't really need to work with all the images just the best ones I try to tag in camera with the protect button. These images appear in PM as tagged so I can filter out anything else and work only with them.
Usually I check all the other images and tag them as well to join the rest. Once all needed images are tagged I assign them the reject, edit or done colors like mentioned above. Usually I do their edit as a batch in LR then open the edited images in a contact sheet (or have them join in the allready open contact sheet so adding IPTC to original and edited in the same run (I use RAW so originals are never overwritten by edited versions). Then mark and send them to customers as required.
If I only need a few images from a shoot I don't even use any of the ratings or colors just tag what needs to be sent (best to do it in camera during the shoot) then I only open them to edit and send them right away. Usually after it is done I mark the sent images with one of the above colors to mark they are done, and if I have time I do mark the terribly poor images with the trash color but I often miss this step in a rush.