• Look in side areas, drawers, and cabinets for glowing resin and ammo. They're often hidden in crates and just slightly out of your normal field of view. They are rarely in cardboard boxes. (FYI, ammo/syringe spawns are variable. If you're low, slightly more drops will appear.)
  
  
• Barnacles (on the ceiling) will try to eat anything, so use them to kill enemies or trick them into pulling up trash so you can sneak past. (Note that they will swallow resin.) Explosives will explode automatically. Save your ammo. Few barnacles will drop loot.
  
  
• You can wear hardhats and masks to protect Alyx from some enemies (but not the fashion police). To wear a hat, put it on as though it's a mask.
  
  
• When hacking the spheres with blue and red lines, you can release the trigger on the multi-tool. This will allow red lines to pass through harmlessly but will leave the blue lines in place.
  
  
• If you just opened a door and don't like what you found on the other side, you need to let go of it first before trying to close it. Otherwise it may not latch closed.
  
  
• The shotgun magazine can hold 7 shells, so just keep loading until full. To lock it, just flick your hand up and it'll close. If it was emptied, you'll need to chamber a shell with the front handle.
  
  
• If you reload the pistol while there's still a round chambered, you won't need to release the slide. To release the slide with one hand, press the upper button (on the Vive). Don't manually rack (pull back) the slide if the breech is closed or you'll waste a round.
  
  
• If you cup your off-hand under your dominant hand while using the flashlight, it will point the light wherever the gun is pointed.
  
  
• You can steal grenades from many living Combine soldiers while they're alive, but those same soldiers usually won't drop grenades upon death. (Consider stashing these.) You don't need to look for the grenade before trying to steal it; just try doing the hand motion.
  
  
• Don't bother stashing bug jars; there's usually one near each health station. (I also always stash grenades over syringes, but I have been known to double-fist grenades even with 2 stashed...)

• Reserve ammo, health, and resin are shown on your gloves.
  
• Your pistol's grip shows what's left in the magazine. One white line at the top indicates if a round is chambered. If there are yellow lines, it means the mag is low but not depleted. You can only put full mags in your backpack.
  
• Shells in the shotgun are shown on the back.
  
• The SMG has a red circle (near the front) that turns black as ammo depletes. (Think donut chart.)

In my opinion, these are the best upgrades, in order:

• Pistol: Reflex Sight (10)
  
• Pistol: Bullet Reservoir (30)
  
• SMG: Laser Sight (25)
  
• Pistol: Laser Sight (35)
  
• SMG: Extended Magazine (30)

I know, I know, people love the pistol's laser sight, but its reflex sight is excellent if you use it right. Bring the gun up close to your dominant eye and look straight down the sight, keeping both eyes open. (Think John Wick.) You can be accurate enough to snipe heavies in the face from across the map or land surprise opening shots on propane valves while still being aware of your surroundings.

The bullet reservoir is the best quality-of-life upgrade. You'll rarely need to worry about the slide again. Just shoot until it dings and then reload. It's a perfect complement to a properly used reflex sight.

Don't get me wrong: the pistol laser sight is great for intense close combat, but it can be hard to see, it's weak at long range, it encourages ammo waste, and it's expensive. You'll have the shotgun by the time you've saved up for it, and for just 5 more resin, you could have had reflex sight + reservoir.

The SMG's precision is low, so get its laser sight but skip its reflex sight.

Don't prioritize shotgun upgrades. Shotgun shells are rare, so you'll probably end up reserving it for dealing with surprises.

• Chapter 1
  
  • Good Grub: When you see an insect with a glowing face in a jar, grab the can labeled "NOT COFFEE" and shake it over it.
    
  • On a Roll: At the playground, grab the red bucket and roll it down the slide.
    Little Slugger: When Russell asks you to grab an item to put on the map, use the small baseball figurine under the PC monitor.
    
  • Eye of the Geiger: When Russell sits down, use the Geiger counter (the yellow box) on his face.
    
  • Mag-Snagger: Use the gravity gloves to catch the mag that Russell throws at you.
    
  • Gnome Vault of My Own: Get the infamous Gnome Chomski and take him all the way to Chapter 10. He's underneath Russell's window on a couch. He can glitch on elevators, so make sure to save beforehand and set him down on a raised surface before using them.
• Chapter 2
  
  • Freshly Squeezed: In the Vortigaunt's lair, grab a heart from the bowl and squeeze it.
• Chapter 7
  
  • Team Spirit: Bring a bottle of vodka through the ant lion tunnel. Don't bother holding onto it through the distillery; just grab one right before you enter the tunnel. You can drop it right after Russell thanks you (and the achievement pops). There's no extra reward for carrying two through the whole rest of the game like I did...
    
  • Near Jeff Experience: This one's a bit buggy, so the easiest way to get it is to drop bottles from the catwalk right after you meet Jeff. Stay right above him for 10 seconds.
    
  • Crustacean Frustration: After the elevator, you'll enter an open area. Right after that is a narrow passage enclosed by chain-link fence. A headcrab will appear and cross a plank at the end of the hallway. Obliterate it before it knocks over the bottles.
    
  • Hold Your Liquor: In the side room in the cellar, a bottle will start rolling out when you open a cabinet. Catch it.
    
  • Flat Note: Get revenge on Jeff by trapping him in the trash compactor and then crushing him. Save right before you crush him.
    
  • Sound Strategy: Load the game and then exit into the tunnel without killing Jeff.