My wife and I will usually split whatever we are carrying. I have a CC she has a CC, I have some cash, she has some cash, etc. If one of us looses something we have a backup. Generally we don't carry too much cash with us other than tips for the guides, which we usually bring in US currency, while on the way from home to a location.
Cash in our destination country we get from an ATM. There is almost always one in the airport and often in or near hotels and they usually have decent exchange rates. Check ahead for extra fees you may be in for though. Our bank is reasonable. This works in Europe at least. Other places I have been I have used US currency (usually in the airport since they are more likely to take it...) but you usually get a poorer exchange rate that way but your change come back in the local currency. Same for the currency exchange, convenient but expensive. Charge cards also tend to have pretty good exchange rate so we use those if we can. Again, if you have one with a low or no foreign transaction fee!
For around town, we carry a smaller portion of cash for use and keep the rest in the safe at the hotel (though this is not always completely safe either it seems). If I am carrying stuff I really want secure (Cash, Passport) I have a security wallet/pouch that tucks inside the pants and attached to my belt. This is for storage only. Anything I plan to use I have in pockets or pack. Likewise, my wife has a neck pouch she can tuck inside her shirt. She also carries a small, cross body purse for the essentials.
We also carry with us, a photo copy of our passport ID page, rather than the real thing. I don't recall having been asked for it other than at the airport but the copy is probably better than nothing if needed and doesn't risk losing the real one. It can also serve to help replace a lost passport I have read.