As for me, I although I don't have to do it, I still did ground myself to at least 90% mil-sim mentality in this server. The only reason that I bought this game (ArmA 3) is because of it's realistic mil-sim aspect that is not so common with other games such as Call of Duty, Counter Strike, Battlefield, and many more.
So, what I did is that:
adjust my weapon sway to vanilla (1.1) in the server's option menu
limit my ammo capacity to 6 mags only for rifles, 3 mags at most for support weapons (e.i. machine guns)
2 grenades regularly and 2 smoke grenades
5 first aid kits
if I'm playing as an Rifleman AT, I'm limited to 2 rockets; one is already loaded to the launcher
if I'm a medic, I bring 5 extra first aid kits ans 2 more smoke grenades
if I'm a sapper, I bring a mine detector, 4 explosives/1 stachel charge, and a toolkit (for disarming explosives/fixing military assets)
if I'm a sniper, I'm limited to 3 extra mags of M320/GM6
I don't wear that over protective armor with kevlar arm protection because it's too heavy
I don't usu long range scopes if I'm not a marksman or a sniper.