What are some of the must have child safety precautions in house with a 3-5 yrs old around?

Protect sharp edges on cupboards and shelves etc. I smacked my head off of a small cupboard when I was around this age and I still have a scar. Also, draws and cupboards, to protect your child from slamming their fingers inside. We have non slam on everything and it's really great! You can get them from IKEA http://www.ikea.com/sg/en/catalog/products/30271274/