I don't use a purse. For many many years this system worked great for me--- there are so many benefits.
However, my life has changed a little bit and I am also having to admit the downsides of this approach.
I use a small, flat zippered coin purse as a wallet. It is about the size of a credit card and I use it to carry my DL, CC, and insurance card plus a little cash. It goes in my back pants pocket. I live in a cold climate and wear a jacket or coat a lot of the time, and many of my coats and jackets have deep and/or zippered pockets, which makes me feel more secure. Depending on the weather chapstick, the cell, car and house keys, and occasionally a small pocket knife either go in a coat pocket or in my other jean pockets. Sunglasses go on my head, in my center console in my car, or have an arm tucked under the bridge of my bra through the neck of my shirt. I generally carry a water bottle or keep it in the car. When I am somewhere where I need more things I tend to have a school or work bag or a lunch pail.
The benefits:
1. No keeping track of a purse--- everything important is pretty much on your body and there is little to take on and off.
2. Purses can be heavy--- no weight on your neck.
3. Less fuss/fits my tomboy personality well.
Problems I've run into:
1. I have a script I have to take 3x a day. It isn't a common script and the pills look slightly like X, so I prefer to keep them in their actual bottle (plus then I don't have to remember to refill a smaller pill container or bag each day). I also have migraines, which means more meds I have to carry on my person, and the two f these things makes carrying a water bottle and sunglasses more important.
2. With texting and 3G, cell phones have gotten bigger, and are more and more likely to get damaged by sitting on them and more uncomfortable to put them in a pocket.
3. Since I do not use a cell as a calendar, and still use a checkbook for larger purchases/medical payments (it adds an additional paper trail to large transactions, which gives me some comfort) I occasionally have to juggle a scraps of paper, big and small receipts, an agenda book, and checkbook when out running errands and visiting the doctors. Sometimes I end up juggling things or overstuffing pockets awkwardly to the point I think a purse would be easier.
4. I'm more prone to dropping my sunglasses.
5. The last thing you want in the summer is to sweat through your clothes and soak your cell and wallet. Not that a purse can't be hot and sweaty, but summer clothes are also less likely to have appropriate places to put things. I don't know what to do with myself when I wear a cotton skirt I have, and I have had to put my cell in rice after a ride in a car with a friend whose AC wasn't working in July.
6. I have lost a wallet, twice in 10 years of doing this. Both times it involved wearing a new or unusual garment and finding out the hard way that the pockets aren't as secure as in other clothes. Once it was a pair of jeans where the wallet continuously worked its way out of the pocket, the other was when wearing a dress to a funeral, wearing a sweater with zip pockets, getting cold and unzipping them to put my hands in and forgetting and having the wallet slide out in the car and then getting kicked out by another funeral goer. Both times I've had the wallet recovered and returned to be by a officer or a good Samaritan, sans the cash in it.
I personally am thinking about switching to a purse, but am having time seeing something I could imagine carrying or being able to adapt to it! I am clueless about it.