As a Year 7 tutor I thought this might be a good thread to start. 
Label all the kids clothes that you would be upset if they lost. One school jumper looks very like another and there will be around 200 new jumpers arriving in school in september.
Mark your child's school shoes and trainers with their name. Clakes only have so many types and there will probably be many kids with identical shoes.
Get lots of very cheap pencls and pens, they will get lost on a regular basis.
Please contact your child's form tutor if you or your child is worried or upset about something. But please don't expect the form tutor to seach for lost clothing etc
or to go to every teacher and arrange that your child gets replacement books for the ones he ruined by tipping water over them ....this has happened to me in the past. 