Dress comfortably. Don't wear clothing that is uncomfortable especially shoes. You don't want to get blisters when you are out hiking.
Gone Hiking

Wear proper shoes. Don't wear sandals or Converse sneakers on a long hike. Get a pair of hiking shoes or boots or at least a good pair of sneakers. Believe me, you don't want to be wearing a pair of 'chucks' on a long walk.

Dress in layers. The weather in New England can suddenly change. There is a saying, "If you don't like the weather, wait a minute." This can be especially true if you are climbing up and down a mountain. I recommend a t-shirt with a sweat shirt or sweater or it and a jacket.

Wild animals. That's what they are WILD. Those guys in that Tacoma commercial that scare away the bears that are eating their food - forget it. Don't approach the animals. Don't feed the animals. Stay as far away as possible.

Stay on established trails. Don't go off the trails thinking you are cool. You may end up spending the night outdoors.

Know the weather. Check the forecast for the area you will be in before you leave home. No fun climbing up a mountain in the rain or snow.

On top of Mount Monadnock

Waterproof matches. If you get lost, you will want to build a fire no matter whether it is summer or winter. The fire will produce smoke and hopefully someone will spot that and find you. It will also help you to melt snow or boil water to drink. Don't eat snow if you are thirsty. It will only lower your overall body temperature much quicker.

Cell phone, if you own one. This is very handy if you do get lost. However, when climbing Mount Washington be sure you are definitely lost or hurt. The patrols are starting to charge people who call for help who either don't need it or didn't take proper precautions to begin with.

A snack. Hey, I get hungry just walking around a supermarket. When you get to your destination it's nice to stop and have a snack or lunch.

Water. You don't want to get dehydrated out on your hike even if you don't think it will take very long.

A friend. Hiking is more fun with a friend. Also, if there is a problem your friend can help you out.

For more safety tips check out https://www.wildlife.state.nh.us/Hikesafe.html