It wouldn't be a fun hobby if there wasn't the temptation to spend lots of money on stuff you may not need. Hiking is no exception.
Backpacks
There are many options for backpacks. My only advice is to use something that is comfortable, organizes your gear so you can efficiently get to things and supports the weight you are carrying. Padded shoulder straps, hip straps (if you are carrying heavier loads to get the weight off of your shoulders), integrated water bladders and million other features can all be worth considering.
Keep in mind that the most expensive options are not always the best. Do your research, ask people about their opinions and try different things to determine what works best for you.
When packing your gear, a good rule of thumb is to assume that everything in your pack will get wet and plan accordingly. Zip lock bags can be your best friends in protecting extra clothing, matches, food and anything else not immune to water.
"Ten Essentials"
A running joke as there are typically a little more than ten items that you should always carry as essential items. Boy Scouts coined the phrase and it is commonly referenced. The intention of these items is to allow you to survive 24 hours in case you get lost or injured until rescue personnel can locate you.
As you gain more experience in hiking you will add many things that are essential to you. This is part of an ongoing process of gaining knowledge that will continue throughout your hiking lifetime.
Pocket Knife
First Aid Kit (See below First Aid section for more on putting this item together. Don't buy a pre-built store kit)
Water (See below Water Treatment section for more information)
Trail Snacks like energy bars or other high calorie dry food that will last awhile in your pack.
Map and Compass
Flashlight with Extra Batteries
Matches and Fire Starter (See below Fire Starter section for more information)
Sun Protection (Hat and Sunglasses)
Rain Gear
Extra Clothing/ Weather Appropriate Clothing
Additional Essentials:
A Whistle- Three short blasts on the whistle is the universal signal for help. You can blow a whistle much longer than you can yell and the sound carries much further.
Watch- A timepiece is an essential navigation aid. Knowing when you start and how long it takes you to reach way points along your hiking plan tells you if your pace is on track or if you need to make adjustments to your pace or plan.
Pencil and Paper- In addition to the one within the First Aid Kit, this is a great way to note trail experiences and gained wisdom along the way.
Insect Repellent- In some areas, during some seasons, bugs can be very prevalent. A rellent with DEET works the best typically. Use it sparingly and make sure you store it in a zip lock bag as the chemical in the repellent breaks down nylon (your backpack) if exposed.
Space/ Emergency Blanket- A few ounces of weight for this lightweigh and compact items is a small trade off if you need it in an emergency. It can also be used for your First Aid kit if someone in your group is injured and shows signs of shock.
Plastic Garbage Bag- A small white kitchen trash bag can be a very useful item for such things as carrying wet clothes, backup to your primary rain gear, tool to catch rain for drinking, impromptu ground cover, or for cleaning up trash found along the trail.
Cell Phone- These days everyone has one. An option for help if reception is available and it comes with a camera.
Backup Battery- These are about $20 and come in handy for resurrecting dead cell phones if you drained it taking pictures or trying to get a phone signal.
Tissue/ Toilet Paper - I suppose one could use a shirt sleeve, bandana, or a fig leaf, but I prefer to use tissue if I need to wipe my nose or other southerly location. Keep your tissue in a zip lock back and have a second zip lock bag for the used tissue.
Extra Boot Laces - Like most things on this list, only are a lifesaver when needed. Breaking a shoelace during a hike is one way for Murphy's Law to check and see who is prepared.
First Aid Kit
Make your own first aid kit instead of buying a prepackaged one. At the very least this way you know what is in your kit. The following items can easily fit into a zip lock bag:
Six (6) Adhesive Bandages
Neckerchief or Triangle Bandage
Two (2) 3" x 3" Sterile Gauze Pads
One (1) Small Roll of Adhesive Tape
Small Scissors
Tweezers
One (1) 3" x 6" Piece of Moleskin (For Blisters)
Small Bar of Soap
Small Tube of Antiseptic
Pair of Non-Latex Gloves
Mouth Barrier Device (For Rescue Breathing)
Pencil and Paper (For Documenting Symptoms and Treatments)
Hard Candy/ Frosting Tube/ Honey Packet (For Diabetic Sugar Needs)
Space/ Emergency Blanket
Water Treatment
In addition to water, have a way to treat water as a backup plan. Remember never to drink untreated water in the backcountry as single celled micro-organisms (giardia), bacteria and viruses can cause serious digestive issues and illnesses. There are many options for treating water that include:
Water Purification Tablets- These are cheap and effective. Some people don't like the taste, but most come with a second bottle now that contains vitamin C that neutralizes the taste.
Purification Filters- This option is expensive and on the heavy side but can be a good investment if you are leading a group or just looking to build up your home emergency preparedness kit. Some popular brands include MSR MiniWorks EX Water Filter, Lifesaver Liberty Water Purifier and First Need XL Elite. All of these examples filter our particulates, bacteria, single celled micro-organisms and even viruses (more of a concern in third world countries). Most of these filters can be back-flushed to be cleaned and in theory never wear out.
Purification Straws- Less expensive and lighter than filters, purification straws filter out particulates, bacteria and single celled micro-organisms. They do only have a certain number of uses before they need to be replaced but that is typically after more than 250 gallons.
UV Light Pens- Mid cost between straws and filters, pens kill bacteria, single celled micro-organisms and viruses. There biggest downside is the need to replace batteries or recharge after about 20 liters or so of water. They are lightweight but will require the bulb to be replaced or the whole unit to be replaced depending on the brand after about 8,000 treatments.
Water Containers
There are two big options: water bottles and water bladders. Here are some thoughts and opinions on both. Water bladders have become very popular but have some drawbacks to consider:
They leak (It isn't a matter of if, it is a matter of when)
When I hike with kids, I like to see how much water they are drinking to make sure they aren't giving me lip service when I ask. With bladders it is harder to keep them honest.
Cleaning. Unless you maintain them and keep the tubing clean and dry when not in use, you will have a mold science experiment.
The advantages are that water bladders are convenient to drink from while hiking. You put your mouth on the straw and drink. They also more evenly distribute the water weight in your pack. Water is heavy.
Water bottles are the original solution to hydration but also have some drawbacks to consider:
You have to dig them out of your pack each time you want a drink.
They can place the weight from water unevenly within your pack.
You can limit some of these issues by using a water bottle sling and evening out your pack load.
Remember to carry extra water and a small bottle of Gatorade to have in an emergency if someone in your group becomes dehydrated or experiences heat exhaustion.
Fire Starters
A Fire Starter can be as simple as a Zip lock bag filled with dryer lint, newspaper pieces and dry wood kindling. I recommend a small tea candle as well. A candle stays lit very easily and maintain a flame under kindling.
Hiking Poles
Some people I have talked to love hiking poles and others hate them. I will leave this item in the personal preference category. There are however some considerations in favor of hiking poles:
If you are backpacking with a heavy pack and planning to cross a stream or be in snow, they should be required for added stability and balance.
When going downhill they can take some of the impact pressure off of your knees.
In an emergency they can be used as a splint or cane.
There are many other creative uses for a hiking pole that can be applied beyond their primary intended use. Most of them are realized by people who left them at home when needed.