How to start an old school sandbox game

From https://www.therpgsite.com/showthread.php?40547-How-to-switch-to-OSR&p=1087083&viewfull=1#post1087083

The Quick Primer for Old School gaming is pretty good.

For more advanced stuff you could check out/google
Ben Robbins' West Marches - was a 3e D&D campaign, but OSR principles
Rob Conley (Bat in the Attic) on sandboxing
Justin Alexander also has good articles on his website on megadungeons & sandbox play

I think the easiest way to start is
1. Get or make a sandbox such as Rob's Blackmarsh at the Swords & Wizardry SRD site - https://www.d20swsrd.com/
2. choose or make a 'home base' starter village such as Hommlet, set in the sandbox, with an Inn or similar start locale for the PCs
3. Place a bunch of adventures, such as the free ones from Basicfantasy.org, with most of the lower level ones closer to starter town & higher level further away
4. Provide rumours to several of the adventures at the Inn/start locale. 2 or 3 is good to start. Only giving 1 tends to train GM & players to expect linear campaign.
5. Be ready to GM whichever of the adventures the PCs seek out.
6. Go to #4. Eventually go to #2 as the PCs move away from starter town, and to #1 if they wander off the map.