As we have had more children, I have been VERY GRATEFUL that I started color-coding things early! It just sort of happened at my house: Ian went through his firefighter/fire engine phase, then David LOVED "Blue's Clues". Ian claimed all things red and informed me that David could have all things blue, and our color-coding system was born! I decided that those colors were pretty close to their birthstones, so from then on I would assign children their color according to their birthstone color. I also assigned Husband and I colors (mostly for calendar purposes).
A pack of markers that goes on sale at school supply time is about $1, and usually has: black, brown, red, blue, green, yellow, purple, and orange. Also, I've noticed that a lot of things come in red, blue, yellow, and green, so keep that in mind as you choose colors.
Color coding people has been VERY HANDY for:
*writing appointments on the calendar: it's easy to glace up and see who has something that day
*cereal bowls, cups: NO MORE FIGHTING OVER WHICH COLOR CUP SOMEONE IS GOING TO USE! After a few times of saying, "I'm sorry you want the _______ cup, your family color is _______." they GAVE IT UP and just used their color!
*toothbrushes: no more mixing up toothbrushes!
*plastic Easter eggs: when we have an egg hunt, everybody knows to only pick up THEIR color of egg, so we have no problems with one person getting most of the eggs while someone else hardly gets any
*re-usable water bottles: everyone has their own color, so no fighting over who it belongs to
*notebooks, folder, pencils, scissors, backpacks, lunch boxes: no more wondering whose school supplies are lying around
For things that I can't buy in different colors, I went to the paint section, I believe, of a certain store, and discovered that they now make duct tape in different colors! So I bought a roll in everyone's family color, and I use that to mark things that are identical or don't have a specific color (toothbrushes, bags of candy or boxes of cereal for Christmas/Easter/Valentine's Day, toys from kids' meals). This is really helpful at Christmas, or any other time a lot of new things come in the house, because I can tag everyone's new toys and then I don't have to try to remember which thing belongs to which person.
Color-coding has been a BIG HELP for me!