Not sure what the OSR is or how to get the best out of it? Got players who aren’t quite sure? One of the best resources that you can get for free is Matt Finch’s Quick Primer for Old School Gaming, which is available for free as a PDF. It’s an incredibly useful distillation of what makes old school play so different from many other types of other play for both players and GMs and acts as a handy reference document even for the most experienced.
Matt distills the ideas for players down into four key “zen” concepts that are easy to read and comprehend, and offers some hints for GMs as well. I personally find myself going back to it again and again to keep the ideas in it salient, and offer it to players of many of my games so that we’re all on the same page for play.
Matt is a well known figure in the OSR community who has not only written Swords & Wizardry and Swords & Wizardry Complete [AL], but also contributed to OSRIC, both of which can be downloaded for free as PDFs from DriveThruRPG [AL]. OSRIC can also be purchased in print format from here. Print copies of Swords & Wizardry Complete can be purchased from Frog God Games.