Step 1: Why You Want a Knife
Step 2: Know Your Knife
The steel: Where the different compositions of each alloy will vary between almost any producer, there are a few that are more common, or a couple of phrases that would be helpful to recognize when you're making a selection.
420 Stainless Steel: This will be one of the most common compositions of metal used in knife making. It offers good resistance to rusting but tends to be a few shades softer than other metals on the market. This does not mean it is bad, however it won't hold its edge as well as some other blades.
440 Stainless Steel: This will be a step up from the 420. It still has the high corrosion resistance, but will generally hold its edge better.
Carbon Steel: Carbon steel is a vague term. There are numerous grades encompassed by that simple phrase, but they share a few common threads. A carbon steel blade will not be as resistant to rusting, and will need to be watched more carefully. They may take a little more maintenance, but overall will be a harder blade and will not need to be sharpened as often.
Unrated: While it is possible that the knife could be homemade, it is generally a good practice to avoid a knife that doesn't list its grading. If it only says Pakistan, or China, or some such on the blade, but will not even proclaim a basic 420 steel it may not even be rated. Knives like this have a tendency to lose their edge quickly and bend without returning to their original shape.Elasticity in a blade is desirable, a knife that can flex but will return to its original shape on its own is an extremely high quality, most knives are rigid and won't flex, but be wary of knives that will bend without going back.
Damascus: The blade featured in the picture is one of the most distinctive blends of metal. Known as Damascus Steel, its comprised of metals with different carbon content being folded together. Its widely valued both for its signature appearance, and the fact that the different metals together offer it a blend of flexibility and hardness. Good Damascus is notoriously expensive, and while high quality can be prone to having the different layers begin to flake with prolonged use if it isn't taken care of.
Step 3: The Importance of Shape
For example, take the knife that won the west, the famous, or perhaps infamous Bowie. First and foremost it is a fixed blade, meaning that it doesn't feature a mechanism that closes it. It has to be kept in a sheath to hide its edge and has a much larger profile, making any fixed blade a poor choice for say, an every day pocket knife. The blade is relatively straight but curves upwards, meeting a section removed from the back of the blade to give the Bowie a finer point. The Bowie is a fine example of a knife that was as much tool as weapon being rather heavy and sturdy, but still having a sharp straight blade, with a narrower tip for stabbing.
There is another variety of knives called skinners. Skinners are used namely to remove the hide and clean game, making them a good friend for anyone who would go hunting or is just trying to catch their own food. They can be fixed or folding which offers a choice between the stability of a fixed blade, or something more compact to put in a pocket or backpack. The blade will generally be shorter, and have more curve to it, and the back of the blade will be straighter and have the cutting edge slop upward to it. This will reduce the knife's penetrating power, making it less likely to poke holes in the subject. Some skinners will also come with a "gut hook" which will be a ground down portion on the back of the blade, with a cutting edge that does not feature a point. These are helpful when a hunter is trying to not pierce the stomach or organs which would risk fouling some of the meat.
Now those are only two specific designs. There are variations there of within their own names, not to mention countless varieties besides. The most important thing to ask when looking at purchasing a knife is, "What will this be used for?". Is it for splitting logs and pretending you're Rambo in the jungle? By all means use the heavy handed Bowie knife and find a ridiculously large, serrated, and mean looking version there of. Is it to open bottles of both cap and cork variety, while still being able to clip loose threads and still have a sharp little blade to open mail or boxes? Then perhaps the multifaceted Swiss Army Knife variety would be more appealing. A knife is a very personal thing, and a good knife over time could take on a legacy of its own.
Step 4: Caring for a Knife
Keeping a knife clean may sound simple enough in theory, but that depends entirely on what kind of knife it is, what it gets used for, its age, or any number of things. When cleaning a knife, avoid fully submerging it in water. Water can get into places that can't be reached easily and begin to form rust. Also if the knife has a wooden handle, or wooden inlays, the wood could swell and warp if it soaks for too long. A soft cloth or a stiff brush with soap and water should be enough for most cleaning. If a knife is beginning to develop rust, a chemical cleaner or light abrasive like steel wool may be in order. Always avoid things like sandpaper or wire brushes, as they could scratch the surface of a blade and create stress points or give rust a place to begin forming. A clean polished surface will be more resistant to corrosion, and make the entire length of steel stronger overall.
Sharpening a knife can take a bit of practice, although there are products that do make easier work of it. Many companies produce stones set at predetermined angles so the blade only needs to be run between them. That is the easy way, but many people still use flat sharpening stones, both for their availability, and the control they offer. If you want to sharpen a knife on a whet stone, the key thing to remember is patience. A basic rundown of sharpening goes as follows.
Most whetstones will come in sets of two, featuring a rough stone, and a fine stone. The rough stone is used primarily to set the angle of the blade, as well as work out any nicks or chips in the edge. This is the stone to use first. Apply a lubricant to the surface, this can be water but mineral oil is a very popular choice, and set the flat of the blade at a 10 to 15 degree angle. Some kits will come with a plastic wedge to help guide the angle, but it isn't a requirement. The idea of keeping it in that zone will allow the blade to still be sharp and preform as needed, without the angle being so fine that it becomes more likely to chip or break. Patience is key. Try to make steady, consistent strokes, moving the entire length of the blade over the stone with the edge leading and grinding down towards the body of the blade. This makes it less likely to warp or roll the "truth" of the blade, being how consistent and straight the cutting edge is. After the edge is satisfactory, use the finer stone in much the same way. The difference isn't so much that the finer stone will put a finer edge on the knife, but rather will polish the section ground down by the rougher stone. This will remove small scratches and fissures in the knife surface that would develop into stress points, and harbor moisture for rust and corrosion.
Step 5: More Than a Knife
A big mention are fire steels. These tools have become one of the staples for campers and backpackers. While it may not be as easy and convenient as matches or a lighter, they offer an additional source of sparks that does not require fuel and will work when wet. Furthermore, most of them will come with a nice flat piece of metal, that can easily be replaced with the back edge of almost any knife.
Multitools are another variety of knife that are extremely popular. In addition to having an all purpose blade, a multitool will combine other useful tools ranging from saws and screwdrivers to tweezers and toothpicks. The trade off with multitools is that they will not be as streamlined or well behaved as a tool specifically designed for the task, but they have a multitude of tools readily available at any given time, where it would otherwise be necessary to carry a toolbox.