At the end of every exhausting, multi-day trek, I ask myself a simple question: How could I have been better prepared?

On my first overnight hike, I didn’t understand the danger of cotton clothing (when it gets wet, it stays wet and doesn’t insulate) and got a touch of hypothermia. Years later, on a late-fall trip, the temperatures dropped so severely that it was the first time I recognized that my 10-year-old, ostensibly 30-degree sleeping bag was no longer insulating against near-freezing temperatures. There have been other great blunders: failing to pack my clothing and sleeping bag in a waterproof sack, resulting in all my gear taking on rainwater (and weight); failing to pack a backup water container, which was problematic when my water bladder sprung a leak; failing to adequately plan secondary shelter while hiking during a storm.

But in all that failing, I’ve found many important answers to my end-trip question, which usually allows for important corrections on future adventures.

Carry backup water

Water is obviously a critical element on any multi-day hike. After discovering that my back was soaked and my previously puncture-free water bladder was empty not long after stepping outdoors, I’ve learned that everything with H2O requires redundancy. It’s wise to carry both a bladder—like a Platypus for easy, while-hiking consumption—and a sturdier container, such as a Nalgene, just in case the bladder fails.

Having redundancy in water treatment is vital, too. While I carry a Katadyn Steripen—a 90-second swirl of ultraviolet light kills the most common microscopic organisms and viruses—you can never put all your faith in the eternal success of electronic devices. So, I also take a back-up option: water purification tablets or a lightweight filter, like the Sawyer Squeeze.

[Related: Survive the great outdoors by making your own drinkable water]

It’s also useful to carry items that extend water’s purpose. On my most recent multi-day hike—a punishing trail appropriately named the Devil’s Path, which includes five of the 35 Catskill High Peaks and minimal flat terrain—it was hard to stay hydrated. I started cramping up after all the vertical miles. Electrolyte tablets or powder packs generally take up very little backpack space and also give water some flavor and a hydrating boost. 

Plan your meals ahead of time

I’ve lugged my fair share of canned tuna (don’t do that—get the lightweight, less obtrusive pouches); I’ve schlepped pounds of trail mix only to return home with half the bag uneaten. The closest you can get your meals to exact portions, the better. (Though I’d much rather carry an extra Clif bar than spend the final day of the trip hungry.)

Approximate meals by laying out each breakfast, lunch, dinner, and snack. If your preferred mid-hike bite is an energy bar and you know you’ll eat two per day, don’t double up and bring additional fuel-up snacks on top of the bars. (Keep in mind that electrolytic powders and tablets are pretty filling, as well.) Dehydrated meals are a good option, especially when you can add hot water straight to the bag and forgo some tableware. The tradeoff is that you’ll need a small backpacking stove to heat up that water.

If you would prefer to limit weight or keep things simple for a two- or three-day hike, plan meals that don’t require a stove (or much refrigeration): breakfasts of overnight oats with dried fruits and seeds, for instance, and some long-steeped cold brew; lunches of peanut butter and jelly sandwiches (which are always amazing on a hike); and a charcuterie platter for dinner (dried meats, hard cheeses, nice bread, and perhaps a small bag of olives for that extra touch).

Prepare for a lack of shelter

On a recent trip in the woods, my friend and I thought about spending the night at a lean-to at the halfway mark. But before departing, we also recalled a lesson from a 2005 trek, which took place during Hurricane Katrina. Sixteen years ago, we’d planned to reach a lean-to. But the storm had come north and taken out a bridge over a river, stranding us on the wrong side and forcing us to pitch a tent on very troubling ground: muddy, sloped, full of trees, and too many snakes looking for dry land.

[Related: How to go ultralight backpacking]

Since then, I’ve always hiked with a tent, though I have always struggled to find a nice compromise between functionality and weight. I’ve carried a single-person 5-pound tent and wished I’d invested in something lighter. I’ve carried something lighter and woke up soaked. This last time, I took about 2 pounds of a Big Agnes one-person shelter and avoided much of the weight and much of the elements. My friend, however, decided to skip the tent altogether, on account of those plans to reach a lean-to. But because of our missing-bridge experience 16 years earlier, he did have a backup plan. And it was a good thing, too, because confusion over where to meet at the trailhead meant we got a later-than-intended start and missed the lean-to. Again. Using his trekking poles, a survival poncho, six stakes, and some string, he built a shelter to cover his sleeping pad and bivy and stayed mostly dry despite some overnight rain. Moral: Don’t ever expect to reach the lean-to.

Wear the right clothing

After getting near hypothermic on my first multi-day hike in New Zealand, I always pack extra (non-cotton) gear. Materials like polyester, nylon, merino wool, and fleece are good alternatives. At a minimum, I stash away long underwear, a fleece (which doubles as my pillow), a clean shirt, fresh underwear, extra socks, and a beanie. It’s miserable trying to relax at the campsite in wet, sweaty clothes from the hike. (Make sure to pack all of these articles of clothing, along with your sleeping bag, in a waterproof bag in case of rain or river crossings.) I’ve yet to justify carrying a pair of Crocs—I just go barefoot at the site. Though I do get a bit jealous when I spot another hiker walking across the campsite with that sort of rubber-shoed ease.

Pack these other essential items

You never want to wipe with a leaf; put toilet paper in zip-top bags. Don’t chance waking up and being unable to move; bring ibuprofen, other essential medicines, and first aid gear. I bring two headlamps; electronics can crap out. Pack a lighter and a knife. A map and compass. A spork and mug. A silver emergency blanket because of that one time you nearly froze. Rope for lowering packs from precarious precipices and for hoisting bear bags. Bourbon because it’s good and concentrated and it’s OK to bring a little civilization into nature.