There are a ton of videos and blogs on this subject. But welcome to my take on the situation. I have only found a few things to be true when travelling and the rest to be crap.
I don’t put necklaces through straws so they don’t get tangled, because I only take one set of jewelry with me so I lessen the risk of losing something (or having it stolen). I don’t take much shampoo in little bottles because it’s far more logical to “buy it when you get there” and in small quantities.
Perhaps this sounds a little rugged and I know we have favorite hair products, BUT the reality is that one exploded bottle of shampoo or lotion in your suitcase can make a mess that’s way worse to deal with than messy hair. And unless you are going somewhere where you know they won’t sell cosmetics, then just buy something when you get there. You often can find better products in places like Europe, that will work better in the water/sun/humidity in that location.
For instance, a pharmacist in Rome noted how pasty I was, and insisted I buy some SPF50. “Blanca, blanca, come here” she told me and shoved the bottle in my hand with some tampons. This was the best sunscreen I have ever used and I wish I could find it here in the states! It didn’t cause me to break out, it was light and it worked to keep “blanca” from being “rosso”.