Pretty much all we did was put some latches on some cupboards that contain chemicals, put plugs in power points and made sure knives and glass bowls in the kitchen were up high. Apart from that we've taught DD1 not to touch some things (eg wine racks, alcohol racks) and taught her to be careful around table edges where she could bang get head (to the point she now says 'careful' to us...).

EDIT - we can't put gates on our kitchen either. When I'm cooking I generally put on the TV or she plays with toys or she will raid the utensils drawer (her fave option).