To make a knife able to serve you a lifetime you have to keep the knife in shape. It's essential to use a knife for what it's built for; use your common sense when handling the knife. Although some knifes are extreme and can endure massive abuse I advise you to mainly use your blade for cutting. If you need to pry something open for instance there are other tools more suitable for these activity's such as a screwdriver or a pry bar.
A well picked knife combined with the right handling and maintenance can last forever.
With maintenance I mean keeping the knife clean and sharp.
Pending on material cleaning techniques can wary but usually a regular wiping of a soft cloth gets the job done. When this isn't enough a hand wash in warm water and some washing-up liquid gives you a new and shiny knife. Make sure to get the knife dry and then apply some grease or gun oil to make the metal more resistant to corrosion. Personally I don't like using petroleum based lubrication's on knives I use for eating or cutting up food. Instead I use olive oil that is a perfect lubrication for knives. One drop of olive oil gives your folder a smooth and tight mechanism. But add just enough oil. Too much only makes the knife sticky and then it'll attract dust that can damage a folders moving parts. Note that it's a good idea to check with the knife maker if you are unsure on what suitable products to use on a particular knife.
A dull edge is often more dangerous and causes more accidents than a sharp and more responding edge. How to sharpen the edge depends on the blade design, material and the sharpening tool of choice. There's a lot of different sharpeners out on the market today. My best advise is to try as many sharpening techniques as possible an then decide witch one that suits you and your knife the best. Sharpening knives is an art that needs practice to get right so just get to it. I would suggest to start out practicing on some cheap blades. If you CLICK HERE you can see how I do when sharpening knives. If you don't wanna sharpen your own blades you can contact a professional sharpener. and they will help you out.
When not in use the best way to store your knife is in a dry and safe place after cleaning and oiling. Older knives with leather sheaths is preferable stored without the sheath. This because there is a small risk that the leather effects the steel.
Keep your edge