In addition to the suggestions to set alerts (which one should do regardless if one is traveling or not), when traveling, there's always the option to notify your credit card company(ies) of your travel plans. This can frequently be done on-line at their website, or a simple phone call. AND some cards are better than others for monitoring spend patterns. American Express, for example, may decline charges that are outside of your normal spend pattern, and contact you immediately, even if you don't have any alerts set.
I always contact my credit card company for the card I plan to use when traveling across country. I let them know what state(s) I plan to be in, and how long I'll be gone.
Some folks may say this isn't necessary. I say, better safe than sorry; it takes minimal time to do. And yes, your credit card limits liability, but why not take all steps to prevent fraud?