I use several favourite handbags and it is a hassle to keep putting the bare necessities into each one (lip gloss, paracetamol, tweezers, breath freshener, plasters etc). I keep these in a clear plastic cosmetic bag that fits into all of my favourite handbags, and when I change bags, I just grab the clear bag and pop it in the handbag that I will be using that day.
I have a few designer bags that I use on the weekend, I have them stocked with some of the essentials, hairbrush, lipgloss, a stash of mad money so all I have to do is throw in my wallet and cell phone. I found that it is really helpful to have a few extra sets of keys, so I can keep them in the extra bag as well.
I purchased a wonderful handbag organiser so when I change bags I just lift the organiser out and place it in the new bag. Consequently I never forget anything. I purchased it from 'I Want One of Those'.
I use two products - one from a craft fair that a friend bought for me; the other is a "Very Intelligente Pocket" from Tintamar. Avaiable in various sizes on the internet.
Both have pockets of different sizes, keeps things from rolling around in the bottom of your bag and the whole thing can be lifted from one handbag to another.
I too put all of my toiletries, girly necessities
into a small pouch. However, I don't use one that
is clear because when I pull it out of my handbag, I don't want everyone to see what's inside. Also, if any make up (powder especially) gets outside of it's case, it makes the pouch funky. I choose to use something that conceals what's inside and it's got a little room in there so that I can throw my keys in and leave the house without a handbag, for those occasions when you really don't want to carry anything, but you also want your lip gloss, compact powder and toothbrush! To others, it looks like a tiny handbag... and only you will know what's really inside.
Have different handbags for different occasions. One for work, one for going out and keep neccessities in it for going out such as lip gloss, hairbrush.