I've never had an issue with ATM use, although I've used some which seemed...worrisome. Sometimes it pays to keep an ear to the ground, since a particular machine or group of machines becomes known as compromised. Some years back there was a good example in Antigua (Guatemala) or Grenada (Nicaragua)--I've forgotten--which was widely-publicized on travel forums. Locals also seemed to know which machines to avoid, but I used the ATM on the sidewalk next door without incident.

I've had credit cards compromised repeatedly in the US--about once every year recently--and occasionally while abroad. Long ago this happened when someone made duplicate carbon imprints in India; more recently when I foolishly gave card details over a long-distance phone line in Central America before cellphones became the norm. Reporting a card compromised and arranging delivery of a replacement can be quite awkward when far from home; I carry multiples.

Traveler's checks are totally obsolete. Even ten or fifteen years ago it was remarkably difficult to cash them, and you paid a high percentage for the privilege. I used to also carry some personal checks and, while stopping by American Express offices in major cities to collect my mail, I'd use them to purchase cash dollars and/or fresh traveler's checks. Those were the days; long gone, along with paying for a trip with smuggled Levi blue jeans.

Having said all that, it's not necessary to leave home carrying all the hard currency you think you might need. There are astonishing amounts of cash dollars and euros circulating around the world, and it's not difficult to judiciously replenish your supply in most areas. Of course this doesn't apply in remote villages or sparsely-inhabited regions, but that's why I carry a stash in the first place--to get me out of an immediate situation. All dollars or a mix of dollars and euros does it anyplace not subject to peculiar rules, i.e., Cuba.

Hope that's helpful.

Mark