I'd seen the stats on the chief causes of serious injuries and deaths in toddlers so we did have stairgates (we have a townhouse, with tiny landings, so would have had them anyway, tbh). Cupboard lock on the under-sink cupboard with all the bleach in.
Breakable/precious stuff out of reach is just common sense, surely - if it'd upset you if it got broken, don't leave it hanging around near a curious child.
Despite all this, we still had the hideous moment when I turned round from the washing up to check on ds, who was playing happily in the cupboard with the tupperware, only to see some blue grains on his lips - flipping rat poison! I didn't even know we had any rat poison. Turned out stupid stupid dh had spotted some under the fridge when we moved in, when ds was seven months, and idiotically decided oh, I know where I'll put that, in the back of a cupboard behind some big stuff we don't use very often so my wife doesn't realise it's there...
It turned out fine, but I'm sure I got a few grey hairs that day.
ds is a mega-fiddler, btw, always has been and still is now. He can't walk past anything without picking it up and touching it. I've said 'look with your EYES not with your hands!' so often over the years I'll probably still be repeating it in my grave.