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You may have heard that New Yorkers are famous for their sharp heels and oxfords, but if you're trying to get a lot done in one day, comfort is key. You'll fit in just as well in cute sneakers or sturdy, low-key walking shoes, and you'll be grateful for them at the end of the day. New York's climate is modified by the whims of the Atlantic Ocean. It can play host to extreme temperatures and surprising weather patterns. Pack clothes that are appropriate for the time of year you'll be visiting, and make sure to look at the forecast for your trip before you leave. New York in the summer is hot, humid, and sunny. Pack skirts and dresses, light shorts and pants, a sweater or jacket for chilly air conditioning, sunglasses, and sunscreen. Light shoes are good, but avoid flip-flops--they won't keep your feet safe on crowded or dirty sidewalks. In the winter, stay warm. Wear a wool or down coat, and add sweaters, thick tights and pants, and sturdy boots. Layering is a classic element of New York winter style, and it's practical in fluctuating temperatures. If you plan to shop for anything--souvenirs, presents, or vintage clothes--don't stuff your bag when you pack to leave. Instead, designate some room for your purchases. You can also roll up a light duffel and tuck it in your luggage, then fill it with your new purchases. Do not walk around with a huge bag full of unnecessary items. They will weigh you down in ever sense of the word. Pick a low-key, practical bag, and keep it close to you. You may need a small wallet, your cell phone, a map, and a camera for the day-to-day. Don't forget recorded essential information (like the name of your hotel and any major planned activities). Bring a phone charger with you. You may need to purchase a plug adaptor for it, if you're visiting from another country with outlets different from American standard ones. Chances are you will be trying to see as many places as possible and will be walking a lot. Don't let yourself get too hungry or thirsty, or you could get burned out. There are usually plenty of carts and shops that can offer you a quick bite, but it's smart to travel with food options, too. If you have a refillable water bottle, bring it. NYC tap water is safe and drinkable. Bring nonperishable snacks that don't get squished easily. Try dried fruits, nuts, and energy bars. Remember that snacks are not a substitute for lunch, so don't rely too heavily on them. New York City trains can take you nearly anywhere you want to go, as long as you can figure out how to use them. You can navigate with a map, but there are many smartphone apps available that are user-friendly and offer information that maps can't (for instance, if there is construction happening in a particular station). Citymapper is reliable, and even tells you the best subway cars to ride in. Transit works for many different American cities--you might be able to apply it to your own city, too. Cash is universally accepted by NYC's famous yellow cabs. Also, vendors across the city have drinks and snacks available all day for cash purchase. If you're looking for an ATM, you can ask at your hotel's desk--they're also a common feature in bodegas and greengrocers.

Summary:
Wear comfortable shoes. Dress for the weather. Leave space in your suitcase. Travel lightly during the day. Plan to fortify and hydrate. Download an NYC transit app. Have access to cash.