We bought all the safety gear with our first. But we didn't really bother as much after that.
Only thing I would say is hot water heater - turn it down just so when they first use taps they don't get scalded, and baby gates on stairs. The kind that screw it to studs in walls. We spent a lot on ours and they lasted for all our kids. Best investment.
Cat litter box. Just make sure if you have a cat, the food and litter is out of reach.
Cords. Just make sure they don't yank lamps, etc. down on themselves.
Anything they can jam their fingers into. Just remove or move higher.
Electrical outlets - we did use those plugs. In fact, we still have them up after all these years.
We switched out our heaters - ours had sharp metal edges. We had to when we renovated anyways, but just check stuff like that.
I basically just watched them - I think relying on safety items can be hazardous. A friend of mine used those foam things on edges of her coffee table and her child tore them off and chewed them.
I also had safe places to put them in a pinch. So I could stick in a swing if another child was into something and I had to tend to them.
Kitchen cabinets - I actually moved stuff up and put fun stuff in them to keep them occupied when I was cookie. Plastic cups and spoons, etc. pots and pans. I just rearranged. That's what I did mostly when they were little. Revamped. It's only for a short while.
Good luck :)