The answer is.... with great difficulty. Unless you are travelling for a year or more, it simply is not worth the effort.

During my travels I withdraw at a US atm, from my savings account at home. Because my bank charges me $5 per international transaction, I withdraw the largest amount with which I am comfortable. Most of it goes into one of those pouches which you wear under your clothes. Each day I make sure there is enough in my purse for that day's planned expenditure.

(Check around at different atm's, because some charge at the US end as well... lot's don't!)

Or you could just use credit cards everywhere. Upside is, you have a written record of your expenditure. Downside is, some places charge more or don't take cards, and I know that Visa adds a (too large) percentage to every transaction. Other cards probably do too. And then there are the (offensive) organisations which will only accept US issued credit cards.

Lifey who has never lost a cent