S.H.
My kids are 4 years apart.
So my daughter was in preschool when my son was born.
We had and have, those plastic draw organizers.
From Walmart.
This is it:
http://www.walmart.com/search/search-ng.do?search_query=p...
ALSO though, I had always explained to my daughter, about her baby brother's development in ways she could understand. I explained explicitly, that a baby can choke, on small things or get hurt etc. So she as well, was cognizant of things. I actually would take her around the room, crawling with her and saying "Look... that small ball, it can be dangerous for brother, it is small enough to get stuck in his throat. Round shapes or ball shapes are not safe." And we'd crawl around on the floor, scouting around for things. It was an exercise I did with my eldest, so she could understand. And she did.
She would be very aware of things, around her baby brother. I did not expect her to be responsible for it, but that she also was aware about potential baby hazards. For me, teaching her this information was proactive and cautionary.
But we also, kept everything non-baby friendly, in those plastic drawers, or plastic boxes.
Things you store small/non-baby friendly objects in.... has to have a cover or lid or something to cover it. If it is just a basket or pencil box, those can be opened very easily and baby can grab it. It is not safe.
I also had, just a clear box for me/my daughter to put things in, as a "catchment" type thing. I kept it in the room we were mostly in most of the time and where my kids played. And I kept it up high enough that baby could not get to it, but my daughter could. So for example: IF my daughter found something on the floor, like say a bouncy ball... she would tell me "Mommy I found a bouncy ball. Not safe for brother..." and I taught her to put it in that catchment box. ANYTHING that was found, that was not baby friendly, went in there. It was easier that way, because I was not about to expect my then 4 year old daughter, to go all around the house putting things away. Nor me, when I was busy. So... that "catchment" box, was the place we'd put the various miscellaneous things we might have found laying around. And then later, when I had time, I would put those things away or organize it where it belonged.
It was very convenient and a good repository for me and my daughter to quickly put things. But yet it was contained, high up and not reachable by a baby. And it had a lid.