I live at the edge of the foothills of the Mogollon/Pinos Altos Mtns in SW New Mexico and hike almost constantly, tho' I'm being forced to slow down some now by my body - I'll be 78 in 2 weeks.
Carry lots of water - on my 1st climb up Cooke's Peak - 2,400 ft elevation gain in 2½ miles - I drank 70 ounces of fluids and it wasn't enuf. Trying to catch up with dehydration after a hike is a miserable chore and very uncomfortable.
In the current transitional season, I always carry a fleece vest tucked into the straps of my back pack and warm gloves in the pack, JIC and don't wear shorts. When I climbed 14,278 ft Gray's Peak in CO in Sept. 2007, I carried a jacket and poncho because of the forecast - and it got very cold and windy in mid-day. That mountain was crowded that day and I was the "only" one I saw with a jacket. Many people turned around and retreated, with blotchy legs and frozen hands. I didn't. That was the end of the season - it snowed the next day.
(I really dislike this forum's system of attaching pictures) Picture is at the summit of Gray's Peak. Wind is blowing the poncho sideways and it was cold. People get too fanatical about weight savings. To a point, I agree - don't carry anything un-necessary, but don't sacrifice comfort or safety for the sake of a few ounces. I "always" carry an emergency kit - detailed in another post - on all hikes now, too, mostly because of my age. It gives me fire, shelter, food, water and light in an emergency and weighs less than 5#.
Haha.....weight savings.....in 1969, a girlfriend and I hiked into Rainbow Camp in Big Sur, CA and spent the night. Maybe a dozen others there and you should've seen the outraged faces on those purists when I put 2 cans of beer in the river to cool off.
That nice, cool brew really hit the spot and was only a 24 oz weight penalty on the hike in only. We did carry the crushed cans out with us.
Good boots are a given. Fuss with them in the store and get a perfect fit. Balls of my feet are wide, heels are narrow, so I have a hard time. Unless you're very fit, pay attention to the weight of them. My 2# (each) heavy hikers feel like workout weights on the trail and I seldom wear them now. I don't like the cutesy little hiking sticks Columbia and others sell, but I do carry a lightweight 6 ft hiking staff (made from a Yucca flower/seed stem) that I can really lean into when needed. At my age, balance and equilibrium aren't as good and it's saved me from many a nasty fall - but not all, unhappily. It's great when crossing streams, too.
Something you never hear about but makes a huge difference....your hip/leg muscles. If you're wearing a belt, press in right below the belt and you'll feel where the powerful thigh muscles attach to the hip bone/pelvis. Push in hard and walk across the room. You can feel those big muscles flexing. Same with butt muscles. Now strap a tight belt across them. The belt restricts the movement and impedes circulation. On a highly stressed hike, that belt will wear you out - wear suspenders to get the pressure off and let those muscles move freely.