Your Swiss Army Knife should outlive you if you take care of it.
My oldest knife is 25 years old, of which 10 years was lost (think Mr Burns' teddy bear). It has a couple of maturity marks on it but it is still my favorite knife.
The top ten rules:
1. Your knife is not a hammer. A hammer is a hammer. Please do not use your Swiss Army Knife as a hammer.
2. Keep it sharp - use a sharpening stone as the blade begins to dull otherwise you will bend a blade when cutting too vigourously.
3. Keep it dry - if it gets wet dry it and leave with all blades out.
(3b. When pulling out all blades do not cut off a finger).
4. Do not use the blade in a moving vehicle. The irony of having to use the band aids in your Victorinox SOS Kit on the 11mm hole in your leg will be lost on you at that time.
5. Keep it clean - I use alcohol wipes periodically.
6. The screwdriver is a screwdriver. It is not a chisel. A chisel is a chisel.
7. If you lose anything from the knife - tweezers, toothpick, pen etc - replace it before the hole is full of very scary stuff.
8. Buy your spouse their own knife so yours is where you left it.
9. The magnifying glass on some of the fancier knives (Swisschamp etc) cannot be used as a solar magnifier to start a campfire but can still burn you in the leg (see 'Irony' in point 4)
10. Keep it lubricated - a stiff blade will quickly become a bent blade. I use model train lubricant.
And remember: The best way to collect Swiss Army Knives is to get a job in Airport Security and confiscate them from people who have not flown since 1973 and are unaware of recent changes to check-in procedures.