Clothes

This one is going to vary widely for everyone -- what they're comfortable hiking in, how hot or cold they get, and, frankly, how much they're willing to spend. But here are some basics and my personal picks:

Daytime clothes

Do not overpack here. This is where a lot of people add unnecessary weight. You only need two sets of daytime clothes at most, and only then if you intend to ever wash one set of them during the trip (which I do).

Avoid cotton ("cotton kills," as the saying goes; it has a terrible warmth-to-weigh ratio; it stretches out quickly, especially when wet; it loses all its warmth when wet; and it takes forever to dry -- if you get in a bad situation, cotton clothing could make it worse). Light-weight synthetics are great, and wool if you can afford it.

Pants/Shorts/Skirt:

I bring one pair of synthetic pants (9 ounces) and one lightweight Smartwool skirt (7 ounces, including shorts I wear underneath while hiking to prevent chafing -- those shorts are a pair of wool long underwear I cut the legs off of when they were worn out).

A lot of people bring a pair of pants and a pair of shorts, or just a pair of convertible pants. I prefer a skirt to shorts at camp for a couple reasons: a skirt makes going to the bathroom really easy, and it's easy to pull on long underwear underneath when the temperature drops (without having to crawl into the tent and change clothes). But the difference is minimal. I could probably lose a couple ounces by getting a pair of very light weight shorts, and some day I might make the switch.

Shirts:

I bring two, both sleeveless or cap sleeved (about 4 ounces each). It's warm enough in the Sierra in the summer during the day that you don't need to worry about warmth as a factor here. My priority is just something as light as possible and easy to wash/dry as I go.

However, there's a case to be made for long sleeves in high mosquito season (July). I overheat easily, so that's a no-go for me, but something to keep in mind. It'd also help with sun protection; otherwise, prepare to be vigilant about sunscreen (and to hear more middle-aged men than you can count say "I hope you're wearing sunscreen!" as if there's a 30-something woman in California who's not aware of sunscreen. But I digress.)

A note about ultralight wool (150 weight): It's fantastic and I love it, but it's crazy expensive and doesn't hold up to the rubbing of a backpack for more than a couple seasons. You can't even consider it an investment piece, since you'll have to replace it sooner than you'd hope. I used to bring polyester tops, which are cheaper, dry fast, and are lightweight, but the smell is impossible to get out on the trail, and after awhile, even at home with a real washing machine. I've made the devil's bargain with ultralight wool now that I've bought and paid for all my other gear, but for a beginning backpacker, this is not where I'd spurge. It's not worth it.

Sun protection:

A hat, obviously, and then something to shade your neck and ears. When I first started backpacking, I couldn't find a hat with a sewn-in neck cover that also had room for a ponytail to poke through. Since then, I've seen one out in the wild, so they must exist. But I already created this alternative:

I started with an REI foldable-brim hat (a fantastic hat: it rinses out with 20 seconds under the faucet between day hikes at home, dries very fast, and is very light and not-hot). Then I took a Buff, and cut it up so that it would attach to the back of my hat and drape down over my neck and ears. I sewed small buttons on Buff, and small elastic loops onto my hat. When I'm day hiking at home, I just use the hat. For a backpacking trip, I button on the buff, so it covers my ears and neck, too. The whole thing blocks sun but is very light and doesn't make me overheat.

Socks:

Here I'd advocate for two pairs (3 ounces per pair for mine), even if you don't plan on doing laundry. You always want to have a pair of dry socks to sleep in, even (especially?) after a long rainy day. I'd definitely splurge on wool. Aside from that, this is a very personal choice. The right pair of socks is like magic; the wrong pair will leave you covered in blisters. Try them out on long day hikes at home (ideally with a weighted pack) before venturing into the backcountry.

Underwear and sports bra:

I bring two of each (5 ounces altogether). You can buy wool underwear for hiking, but I don't bother. I just bring lightweight underwear that I know fits well and doesn't ride up when I move around. I'd suggest not-cotton if you're going to wash it on the trip -- cotton takes too long to dry. But I found out by accident that if your underwear has a cotton lining in the crotch, rather than polyester, it will clean up better. Polyester can hold onto smells even when clean.

As for sports bras, you don't need anything high-impact, so I weighed all of mine and just bring the two lightest. And I use one of them as a swim top (along with a bikini bottom, which is 1 extra ounce).

Nighttime / cold weather / rain clothes

Fleece / Puffy:

When I first started, I got a fleece on sale and used that for chilly nights in camp. That worked totally fine. Sure, it was heavy and bulky (almost a pound, I think), relative to a down jacket, but it was a helluva lot cheaper, and there's no reason to splurge until you know you love backpacking and you're ready to spend. I still use the fleece all the time at home.

I switched to a Mountain Hardware Ghost Whisperer down jacket, also on sale, after a couple of years (7 ounces and rolls up really small). If you're ready for an upgrade, I highly recommend staking out the REI sales and snapping one up. Just be sure to keep it in a dry bag and away from any water -- it will lose all its loft (and ability to keep you warm) if it gets wet. Also be careful about rubbing it against granite or other rough surfaces. Ultralight equals ultra fragile.

Sleeves:

For chilly mornings while hiking, I took a pair of knee-high socks and cut the toes off. If you put them on your arms upside down, they work great as sleeves. Then once you warm up from hiking, you can pull them off and stuff them into your hip belt without even stopping. I think you can buy sleeves like this, but why spend the money if you have some old socks lying around?

Long underwear top and bottoms:

Great for chilly nights at camp, and also for sleeping. (There's no need to also bring pajamas -- your long underwear is unlikely to get dirty/sweaty like your hiking clothes, so it'll still be refreshing to sleep in.)

I go with ultralight wool (9 ounces for the set), because it's soft, warm, and light. There's less a risk of it falling apart, since you're not strapping a backpack on top of it, so I think it's worth the investment when you're ready. But you can definitely get a cheaper synthetic option, and that's what I started with.

Warm hat and gloves:

You could probably get away without these, but I'm a wimp about the cold. I just bring a hat and fingerless knit gloves that I've owned forever (3 ounces altogether). I use the hat often, and the gloves rarely. My down jacket has a hood and hand pockets, so this is mostly about comfort and freedom of movement.

Rain gear:

Some people swear by "real" rain gear -- meaning a full rain jacket and pants. They get to stay dry while they're hiking, which is a worthy goal.

I prioritize wearing all quick-dry clothing anyway, so I'd rather just get wet while hiking and change into dry clothes when my tent is set up, knowing my soaked clothes will dry out pretty quickly. This philosophy bit my in the butt one time, when hours of steady rain were combined with a sharp, cold wind. I was pretty miserable by the time I got to camp. (It wasn't so cold that I was in any danger of hypothermia, and I had dry clothes to change into if it was.) But even after that day, I still wasn't convinced to bring rain pants on future trips. And without the wind, I don't mind the rain. To each their own!

I do carry a Patagonia Houdini -- a lightweight rain jacket (3.6 ounces). Mostly I use that if there's a shower starting when my camp is already set up, and I'd like to stay dry just long enough to grab all my gear and throw it in my tent. I'll also use it on the very rare occasions I have a fire at camp, since I'd rather get smoke smell into that jacket than my down jacket, which would be a lot harder to clean when I get home.

Thoughts on weight

With this setup, I'm carrying about 42 ounces (2.6 pounds) of clothing, in addition to what I'm wearing. This stuff really adds up, weight-wise. I could save about a pound if I only had one set of daytime hiking clothes. That's a pound I'm willing to carry for the luxury of washing one set of clothes while I wear the other set, and to always have a dry change of clothes in my pack. Your mental calculus on this will vary!