What's the weather like over there during the time you want to go? Consider the activities, your wardrobe, and your temperament. Depending on the season, your destination may be in a rainy, snowy, or typhoon season where a lot of things may be closed or cancelled, and you'll have to bring or buy extra gear. Also, some places may have shorter days during certain seasons, but if you're traveling, you most likely want more time during the day. I joke that I have an "intolerance for imperfect weather" but let's be real: there's a lot of truth in that. I avoid the bad weather if I know the destination typically has extreme weathers, especially humidity and heat, and rather go in the fall/spring where it's usually milder and nice. Save the winter/summer for places with generally nice or stable weather (ie California).
How long would you need to stay there? You probably don't want to drop $1k to go international and do just a weekend trip there. Realistically, how long would you need to stay in that city or country to get the most of out your trip? Also consider the time of travel. If you're arriving at the airport at 6pm and go straight to the hotel and sleep, you probably shouldn't count that as 'day 1.' Make sure you're allocating enough days to see what you want to see.
How much is your trip going to cost? Traveling is costly- flights, accommodations, meals, tourism attractions, transportation, shopping, leisure money, unexpected payments(<-- this WILL happen). You also have to consider the cost of living for that area. For example, your meals in Vietnam is probably going to be much cheaper than your meals in New York. Don't blow all of your money on one place. [I'll do a future post on tips on paying for your trip.]
Do you know the language? Obviously if you're traveling domestic, this doesn't apply. If you're traveling internationally, most major cities will know some broken English but not always. True story: I was on a train in Italy on our way to Venice and we needed some help. We knew no Italian, and literally no one in our entire car AND the car next to us knew English except a teenage student who basically saved our lives. If you have some time, download Duolingo and try to learn the basics of the language. Pro-tip: In Paris, most people know how to speak English but they refuse to help if you don't even try to speak basic French. Also, if you're still reading this, in all honesty, you should be traveling to get a sense of new culture, history, and perspective... that includes the people and their respective language.
Who are you traveling with? Similar to weather, consider your activities and the temperament of the city. Food for thought: Vegas might not be the best place to travel with your family if clubbing and drinking non-stop Fat Tuesdays is on your to-do list there (unless your family is into doing that together, then, to each their own). Additionally, if you're planning on traveling alone, be smart about where you're going! This is not the time to overestimate yourself. Here are two lists that you may want to consider: Best countries for solo travelers, and the safest countries to visit in 2017. If you want to be extra safe, I'd recommend reading up on current events of that country as well (natural disasters, politics, protests). [I'll do a future post on tips on how to solo traveling + travel buddies.]