Ask questions. Do a little research before agreeing to a group trip—especially if you don't know the other participants that well. How will you be getting around? Where will you be staying? Does everyone have similar budgets? This is particularly pertinent if you are on a tight budget or you know you are picky about your travel accommodations.
Compare your travel styles. On trips with just one or two friends—especially trips that last more than a weekend—try to pick someone with a similar travel style. Regardless of whether you will be sharing a room, you will certainly be sharing a holiday. If you know that you only enjoy active vacations with lots of hiking and little drinking, but your friend's perfect trip involves lounging on a chair by the beach with a pina colada, then you might not be the best match. If you do decide to go together, however, just make sure that the chosen destination can meet everyone's needs. It's perfectly fine to spend the days apart, then meet up for dinner at night.
Realize that with travel, opposites do not (usually) attract. If you're sharing a room, travel style becomes even more important. The more you mesh, the less likely you'll end up clashing after a few nights in the same room. So if you are messy, bunk with your messiest friend on a group trip.
Seriously consider an all-inclusive. These days, many of the most discerning luxury travelers are checking into select all-inclusive resorts. Here, you'll find high-end amenities and chef-driven cuisine at restaurants with a la carte menus and top-shelf liquor. The only difference is that you don't have to pay a tab and tip at the end; you can eat and drink as much as you want for a pre-set, per diem rate. Vacationing with a group of girlfriends, especially across different income brackets, can be so much less stressful when you don't have to worry about splitting a tab.
Have that budget talk. If you're traveling with friends that have different amounts of disposable income, and you haven't booked an all-inclusive, make sure to have a chat about individual travel budgets before you depart. Establish a mutual understanding of what people can and cannot afford when it comes to dining and excursions. This will help keep hurt feelings at bay on the holiday.
Schedule downtime. Regardless of who you are traveling with, nearly everyone needs some downtime. Leave a few afternoons free to keep everyone smiling throughout an otherwise planned-out trip.
Respect people's limits. This is especially important for group trips where you may not know everyone personally. If you like to do every thrill-seeking adventure on the planet, this doesn't mean everyone in your group does. Be wary of your traveling companions' feelings and comfort limits. Show some empathy rather than peer pressure when it comes to talking your sister's best friend into skydiving on the destination bachelorette party.
Discuss the destination. When choosing a destination, make sure to have an in-depth conversation about what each person wants out of the trip. This will be most important on trips to areas where one activity predominates over others. If half your group wants to spend a weekend shopping, and the other half wants to get multiple spa treatments, but everyone loves foodie restaurants, then consider a trip where you are staying at a hotel known for its spa in a big city known for its food scene.
Make a must-see list before leaving. When traveling with a group, it can be easy to end up going with the flow and missing out on something you really want to experience. To avoid this, do some research before leaving on the trip. Set your intentions, and make sure to include them in your itinerary. You don't want to come home feeling resentful that you didn't catch the one place you really wanted to visit.
Be flexible and open-minded. Traveling requires flexibility and an ability to adapt to the unexpected. Traveling with friends will demand even more of this mindset. Expect to get irritated with your travel companions at some point on the trip, but remember this is normal. Try to move past the experience as soon as possible, rather than dwell on it. Keep an open mind and a good attitude and you'll do fine. In fact, you'll have a blast!