Use tons of lip sunscreen or chapstick with sunscreen to prevent cold sores.  Fallene makes a good lip sunscreen (I put it in the SkinTour High Altitude Sports Booster Pack, but you can buy it individually).

And take your prescription for Famvir or Valtrex twice a day for 5 days at the first sign of a cold sore. Call your primary care or dermatologist for a prescription if you don't have one. Take it with you when you travel!