1. "Ammo Lasso" - Imagine getting caught into a lasso (except, it rejuvenates bullets!). When caught by this "lasso," you can move around (iirc, it has a 5m range) and if you're by a wall/obstruction, you can wrap right around it and CONTINUE to receive ammo until maxed or interrupted. So if you're getting ammo and you start getting shot at, move to cover if there is any within 5m. With the consumable Resupply Box, you can receive it's ammo through walls immediately (without having to go near the box to, first, get "lassoed") AND change weapons through walls. (P.S. A lasso is basically a rope that has an end that is formed into a loop, or circle)
2. Reload On-the-Go - You can reload your currently equipped weapon while entering/hijacking from the PASSENGER door, regardless of how long it takes to reload. As long as you hit the reload key before you enter the drivers seat, you'll reload your weapon no matter what the TTR (time-to-reload) is. Note: Normally, as a passenger, you can reload your weapon, without having to stick out the window. You can also do this while hijacking from the driver's side, but your TTR will matter. So if you enter the driver's door, then, not only will you have less time to hit the Reload key, but the weapon's reload time must be short enough for the "on-the-go" reload to occur.
3. Look Back/Back Grenade Throw - Go to Options and bind a key to "Look Back." Now you can look back with that key! To throw a grenade backwards, cook/hold the 'nade and then press and hold the look back key. While looking back, release 'nade. Note: You can only throw back if you're, FIRST, cooking/holding the 'nade. You can't already be looking back, before cooking/holding the 'nade.
4. HVR-Accuracy and Piercing Mod (CAP40 'Sergeant'/Colby Commander) - Hugging a wall minimizes all accuracy loss, giving you HVR accuracy... to a wall. You'll be able to hit that same spot on the wall, so long as you manage recoil. Since the Commander and Sergeant can pierce, you can put that accuracy to use by shooting through windowed/metal doors (doors on buildings/fences/walls, that require the action key to open). Someone 40m out in the middle of the road with you? Whip out a shield, crouch, and lay waste as your enemy questions, "Who is shooting me and how're they so accurate???" (Yes, those weapons can shoot through those consumable shields!) Someone behind a blue ticket booth? If you used Spotter (Character Mod) or have them tagged via Tagger (Weapon Mod), then you can track 'em and shoot 'em with HVR accuracy! In the spoiler, I've included a video proving the effectiveness and my understanding of this trick. There is also a list of things that can be shot-through with the Piercing Mod.
5. Throw/Launch Grenade further - If you jump and throw/launch a 'nade before you reach the apex of the jump, then it'll fly further. Sometimes those heavy Frag 'nades could use an oomph--throw that 'nade at a certain angle, while jumping, and you've got yourself a faster/further 'nade throw... but don't mess up like I did in this gameplay video of me...
6. Enemy Spawn Detection - Whenever a spawn-point is blocked due to an "enemy being near the location," it... doesn't necessarily mean they are near. In fact, it can also mean that the enemy has picked that spawn! That's right. The enemy can be on the SAME spawn map as you (the opposition my share a couple spawn points with you, depending on where y'all died) I knew this because I clicked a spawn point about 40m apart from a "blocked" spawn and then I spawned and looked in the direction of the area that was allegedly blocked due to an enemy being near... Turns out they spawned just as I did (their name was temporarily grey; spawn protection was active); they weren't near that spawn-point at all--technically, they were on the spawn screen as I was. With this, you can conclude that when an enemy dies, as you die, you share the same spawn timer.
7. Fall Break (No gravity damage) - While near a ladder, pressing the Action key just before you hit the ground, allows you to grab onto the ladder to break your fall entirely! Also, by minuscule chance (this'll happen most accidentally), you can bounce-off/bank-slide-off (idk how to explain bcuz its probably a bug, but thats how it can look) on an edge of a surface to immediately reset the velocity at which you fell.
8. 'Nade-to-Weapon Sooner - Instead of waiting for the animation to finish after throwing a grenade, you can, as soon as your 'nade is in the air, swap to your weapon (scroll up for Primary and down for Secondary). Doing this will skip the animation that plays after you've thrown your 'nade and will move on to your weapon-equip animation. Keep in mind, the speed at which you pull out your weapon is based on the weapon you are switching to (i.e. each weapon has a "time-to-equip" before you can fire)--so you'll still have to deal with that. Now, imagine: LowYields-to-SNR ... 'Nade Barrage!
9. "Kempington Shuffle" - While aiming, lean in any direction. Then press the shoulder switch key repeatedly while moving. You'll look like you're dancing! Looks funnier if you do it while looking all-the-way up/down.
10. "Jesus, take the wheel!" - You can teleport into a vehicle, whenever trying to enter through one of its "blocked" doors. Either when the vehicle is tilted on it's two wheels, doors are blocked, or even when it's in the air (so long as you are within range of activation, about 4m), then you can and will teleport into it. While on foot, I was rushed by an enemy (who was in a vehicle) and, luckily, as he slid toward me (with the drivers side toward me), he got out and was close enough to me AND the driver's door that when I press F (action key) I was then warped into that opp's stolen car (bcuz the door-way was blocked by opp) and drove away! Probably one of the funniest moments I've had!
11. Sneaky Takedown - After finishing an objective, if you've seen the enemy leaving for the next objective, then you can assume that by the time they get to that next objective, they will think you and your team are coming from the same path they took (East, for example). When heading to the next objective, instead of heading East, you can take the long route (Go North, then East, then South to the objective). When you're 80m away from the objective, just exit your vehicle and go on foot. You'll then be able to take 'em out from their back! Muffler (Vehicle Mod) makes this method easier, allowing you to get closer sooner, but it can be done without it.
TheSxW made a good point about the range at which you should exit the vehicle, for number 11. Should be at 80m.