A non technical answer: Don't interact with other players and don't give out any personal information.
Use a unique and non-memorable username in steam and in game. Don't use any of the social functions in steam.
It's often overlooked that the biggest risk to personal information is the person themselves.
(Obviously you need to give some information to Steam for purchasing, and others have shown other methods to limit what information is sold about you as much as you an. It also depends where you reside - the EU has better protections than most)
A non technical answer: Don't interact with other players and don't give out any personal information.
Use a unique and non-memorable username in steam and in game. Don't use any of the social functions in steam.
It's often overlooked that the biggest risk to personal information is the person themselves.
(Obviously you need to give some information to Steam for purchasing, and others have shown other methods to limit what information is sold about you as much as you an. It also depends where you reside - the EU has better protections than most)