I use colours for the different calendars in my view: my wife and I can see each other's calendar's and I run/share more than one for the multiple roles I have!
My work and personal calendars are green.
My wife is blue
Family commitments like church, play dates, date night in Orange
Band work - rehearsals, gigs in Purple
Anything in Brown is a "pencil" - a shoot that client has optioned me for - so I need to be aware of - but not 100% committed to until contracts signed - allows me to hold the commitment but also chase for closure if another client is enquiring about my time.
Finally, Liverpool Football Club fixtures are of course in RED