What to Wear
What you wear hiking depends on the season and on individual taste. Because of this, I am reluctant to make many suggestions but perhaps a few are in order.
Wear layers in any season where you may need to adjust for temperature changes. This means changes in environmental temperature and changes in your personal temperature. The weather at the bottom of the mountain may not be the same as the temperature at the top. I usually bring a warm jacket or vest with me in addition to the layers I wear. As you exercise, you will get warmer. In some cases, you will get much warmer! Layers allow you to shed some clothing to adjust for this situation.
Do NOT make any of these layers cotton. Cotton does not wick moisture it just absorbs it. Whatever moisture it absorbs it holds. At the very least this will make you uncomfortable. At the worst, the sodden cotton will get cold and chill you.
I NEVER wear shorts on a hike. The Catskills have stinging nettles, biting mosquitoes and deer ticks that carry lime disease. However, I know many experienced hikers who often wear shorts in the summer even on long bushwhacks.
During the winter, traction and deep snow on the trails can be a problem. Different products are on the market that increase traction by placing "studs" on the bottom of your shoes. For the best traction on icy mountain surfaces, crampons that cover the entire bottom of the foot are a good idea. These do not have to be the $150 ice climbing variety but a good quality pair will last for years. Snowshoes may be equipment but you do "wear" them. There are definite differences in all brands from the recreational model to the ascent models. Many ascent models have a "kickstand" to elevate your heel to relieve calf strain on steep ascents.