Reddit mentions of Child Proof Locks for Cabinet Doors, Adjustable U-Shaped, Door Latch 4 PCK White

It differs for every family, I guess, but here's what we did. First, remember that they grow in stages, so you don't need to baby proof everything at once. OTOH, two toddlers can be surprisingly cooperative, so don't be surprised if they figure out how to operate top and bottom locks on a gate, for instance.

So, start with the sudden death stuff. Cover electrical outlets, secure toxic cleaning materials, lock drawers with knives, secure furniture to the wall (you would be amazed how easy it can be to topple a book shelf from the bottom), cover and gate swimming pools and ponds, gate off stairs, put barriers around fireplaces. Look around at floor level, and look for anything you could reach, eat, break, fall on, or otherwise interact with and suffer harm. Securing electronics is not enough - cables are tempting chew targets.

As they toddle, you may want to protect pointy corners on furniture or fixtures. My twins generally pulled off and ate the rubber bumpers on corners, so that only lasted long enough for them to outgrow the likelihood of falling and losing an eye.

Door bumpers that prevent slamming on fingers (inner and outer edge of the jamb) are definitely worth getting because doors are fun and little fingers are very fragile.

Lastly, look for precious things. Safety first, value second. Put precious items up out of reach, but remember they have to learn about fragile things and some breakage is unavoidable. It's not the end of the world.

One other thought: get plenty of spare electrical outlet covers and door bumpers for visiting friends and family. You can take care of the sudden death stuff in most environments with just a quick go-round; don't expect everyone to toddler-proof their homes, and don't expect people with single kids to understand that multiples are different.

This probably all sounds intense - it doesn't have to be. Just start at ground level and grow with your kids, and teach then from an early age that wires and holes in walls, and sharp things in kitchens, are not to be touched. Good luck!

Edit to add some specifics:

• Standard plastic outlet covers. Make sure it's stiff when you insert it (hyuk, hyuk) because kids will fiddle with them otherwise - they'll see you remove them and try to emulate you. This goes for other stuff like gates too.
  
  
• Drawer clips - we used pretty heavy-duty clips (like these but not quite) for kitchen drawers. Don't trust the double-sided tape they come with - I had to screw them to the drawers. Tried various in-drawer latches and magnetic ones, and none worked properly. Then something like this for cupboards with poisons or dangerous appliances - other latches just didn't work reliably - these have been completely toddler-proof for a couple of years now.
  
  
• Gates - we put them on each walkway out of the lounge, and on the nursery door, so they could be kept within one room at a time. Didn't bother with the stairs, but we did make sure the gates were adjustable and removable so we could take them on holiday for blocking staircases.
  
  
• These on any door that can bang in the wind or be played with. Which is to say, nearly every door in the house. I have a colleague whose little girl had a finger severed by a slamming door, so took no chances.