Always wear uniforms for the side of the faction you are playing to avoid being team killed by accident.
You do not need to be able to sprint. Maybe a lil for quick get to covers but you need ammo more than you need to be able to sprint.
You do not need a pistol, but by all means keep it if you want.
It is recommended to create multiple types of loadouts for each role.
Example: if you role is AT, you could have a kit for Autorifleman-AT, explosives-At, paratrooper-AT, Underwater-AT, Marksman-AT, Urban-AT, etc
Always wear a uniform that is easily identified as friendly.
5 x First Aid Kits
1 chemlite of faction color
Always have a scope. Either in your inventory or on your weapon. That can help you fire at targets up to 300 meters.
Always take a laser sight for night ops so you can identify targets and your location.
Always take a silencer for your weapon. Either in your inventory or on your weapon.
If your a marksman or sniper always take 2 scopes. One for long range and one for 300m or less.
If you can, take ENVG II instead of NVG
These enable you to use thermals. I do not advocate using them all the time.
But if you can not find a shooter then they help see the shooter through bushes and trees or in windows.
KigBag is great.
But if you have the DLC for it I recommend the Viper Harness
Always take a Rangefinder or Laser Designator
Always take a GPS
Always take a compass
Always take a radio
You need this to be able to use ingame comms.