I not only use the ziploc bags, but I don't carry full size containers. I use samples! You can get free samples of so many "personal care" items, I pick them up at in-store demos and there are thousands of websites that will direct you to where to send away for free samples. I have a full drawer just of sample-size items that I use for traveling, that way there's less to spill, it's harder to spill, and if it does spill I didn't lose anything of value (i.e. a full bottle of shampoo). Examples of what I pack sample sizes of for traveling: shampoo & conditioner, lotion, toothpaste, deodorant, perfume. Another bonus: nothing to bring back home. Just think of how much room that saves in your suitcase for souvenirs!
I also try to use wipes if they are available, such as sunscreen wipes, bug repellant wipes, and sanitizing wipes. Easier to carry around the parks too, just toss a couple in your bag or even in your pocket each morning.