Make a budget and stick to it. When you’re traveling by the seat of your pants you may be tempted to spontaneously splurge on a four-course meal or neat souvenirs. Depending on where you’re traveling and for how long, small spontaneous spending decisions can quickly add up, costing a significant portion of your trip’s funds.
Stick to your budget, if nothing else. Running out of spending money is a sure way to ruin any trip.