I bought one of these filing cabinet boxes for each DS and labelled each compartment with English/maths/Geog etc for them to sort their books easily at home.
One thing I still find odd is the lack of text books! There seem to be tons of handouts and the school 'suggest' certain books for you to buy as supplementary, but few actual books! I also bought some A4 clear zip-lock bags which are useful for subjects with loads of 'bits of paper' or additional small books (vocab books) like Spanish to keep it all together.
I bought several rolls of sticky back plastic as every new year they have to cover their exercise book though I cheat by taking the cover of last year's re-naming it with the new year and sticking the whole thing onto the new book
. It tends to be, like maps on the Geog one, Spanish style stuff and flags on the Spanish one etc. They're not 'marked' on their effort, incidentally, it just personalises it and makes it easier for them to spot when the books are handed back out after marking.
Get a pack of those clear plastic A4 'bags' with holes punched for filing down one side. Useful for keeping posters and single bits of work safe (like when H/W is making an information leaflet about a local beauty spot and so forth)
I used a soldering iron to brand their names on things like calculators to discourage theft.
Depending on how techie your school is, set up files on the computer to file work in a findable way! Like Y7- Geog, Y7 History etc. Been very useful I admit with DS2 as I've been able to see what DS1 did with the same work 2 years earlier.
Be prepared for much less interaction with the school. At ours you can go the whole year without meeting their tutor unless s/he's one of their subject teachers whom you'll meet on parents evening! In theory, they keep the same tutor all 5 years but DS1 is on his third and in Y9. I should add you can quite easily arrange to see a teacher should you want to but our school doesn't give out teachers' emails, which is fine, but individual teachers may give theirs to you if necessary.
Accept the possibility of peer-marking! The fazed me a bit at first but I can see the point of it now.
You may never meet your DC's 'best friend's parents!
And velcro is fine at our school. Even DS1's shoes are velcro! And he's 14!