Kids
I only buy plain white socks - for summer or sports and plain grey socks - for school and under boots / jeans , makes sorting so much easier for 3 DC
Packed lunch boxes set out night before with all ambient items already inside like banana / cereal bars - I make the sandwiches fresh in morning but put the chopping board , knife and loaf of bread out beside the lunchboxes so everything is to hand
School bags organised the night before and lined up in the hall with the matching child’s shoes in front of it
Activity bag always in boot of car for toddler if eating out / visiting people on spur of the moment - Small rucksack containing Activity sheet placemats , small toys , crayons, stickers , hand wipes .
DC have a spare set of wellies each in boot of my car in a bag for life for impromptu outdoor walks
For school items I just use black Sharpie marker and write first initial and surname on care label , doesn’t wash out and v quick , saves faffing with name stickers.
I write names inside school bags and lunch boxes in black sharpie too.
All clothes laid out night before 7 days a week , not just school days , just makes life so much easier.
OTHER TIPS
Birthday reminder book in drawer in kitchen with a stash of the 10 for £1 cards from card factory stashed in back , always have something for last minute occasions too this way
As other people have mentioned cheese on toast my quick lazy version Is - toast toast as normal in toaster , while that’s in I grate cheese into a bowl zap in microwave for 30 seconds then spread the melted hot runny cheese over the popped toast - exactly same as grilled toasted cheese but less time and mess
Always have a spare phone charger in the car which is handy for in car charging or visiting other peoples houses , bought a brightly coloured one so I know that’s the CAR one and it never comes back into my house 
Keep a roll of bin bags in a drawer upstairs for impromptu decluttering sessions , also handy for any sickness nights spread binbag on floor beside bed then towel then basin to stop carpet getting messed