Be willing to compromise
Not every set of friends will like doing exactly the same things all the time (that would be weird). There will be things that you want to do that she doesn't and vice versa. If you really want this trip to work out, you're going to have to be willing to compromise at certain points. If she's been in every souvenir shop, craft market and megamall for you, you can hit every art gallery and museum for her — there needs to be a balance.
If you have something to say, say it. The more you hold something in — the fact she keeps you up every night on Skype with her boyfriend, how you think she should be paying more for your shared hotel rooms — the more resentful you're going to become. We're not suggesting you get confrontational, but good, honest communication will save you both a lot of frustration and make the trip that much more enjoyable.
Not every detail needs to be planned out (it's a good idea to leave room for some spontaneity), but if you talk about what you'd both like to do before you go, there's less chance someone ends up disappointed. Before you go, each jot down your top five must-dos on the trip or at least what you hope to get out of the trip (relaxation, adventure, etc.). Once you both know what's important to the other, you can work out a plan that encompasses some of what you both want.
It can be easy to get selfish on a trip, especially a short trip. If you only have one week, you're going to want to pack in as much of what you want to do as possible. This is understandable, but there are two of you. The key to the vacation going smoothly (and the two of you still being friends later) is to be fair and know that for every activity or restaurant that she picks, you can pick one tomorrow.
Don't bring baggage
You'll obviously have luggage, but we're referring to emotional baggage. If you have lingering resentments about your friend (she was late for your last four dinner parties, she flirted with a guy you liked last New Year's Eve), don't bring them on the trip. If there's anything pressing to clear up between the two of you, do it before you get on the plane or in the car. The last thing you need is to let yourself get worked up over something in the past and have it ruin your trip.
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