I use often quite detailed keywording, along with IPTC Subject Codes, which as they are searchable in LR are another quick way to differentiate images by category. I then use Collection groups and Smart Collections to auto sort images into a whole range a subjects and groups. I do a lot of Aviation photography, so my Keywords for those would include location and show details, aircraft types and manufacturers, operators, and any other pertinent information. The Smart Collections are useful, as of course they can pull the same images into different categories, so you don't have to remember where to look for anything. Smart Collections are really good, as once you get used to how to do it you can generate some really complex sort parameters.
I use Colour labels, although you can use any text, not just colours in the labels, to denote the status of images. Unlabeled images are unprocessed, Green are finished images, Blue are images that are intermediate stages, So a RAW file that needed further processing in PS would be Blue. Purple are my Print proof copies ready for printing, Red are rejected but processed images. I do use a couple of text labels for specific purposes too. I also use star ratings too. I apply the same to things like the kids sports and the odd few photographic jobs I do for others.
I have only a few normal Collections, Most of those are actually the Print Collections generated when you save a print in the Print module. The great thing about that is that I can generate a proof copy at the correct aspect ratio and chuck it in the corresponding Print Collection and it will be ready to print if I then open it in the Print Module, without the need to apply the preset to it. Handy if you are processing a series of images, but are not going to print them immediately, but as a group later. Just select them in the Print Collection open the print module and print.
Alan