Store your knives so the blade doesn't hit or rub against anything. I use a magnetic strip, but you could also use a knife block or a non-slip tray in a drawer that keeps knives apart.
Don't let your knives soak in the sink or sit on a wet sink. Wash and dry them as soon as you can.
Don't use the knife edge to scrape food from your chopping board. It will damage and dull the edge. If you want to use the knife, turn it over and use the other side of the blade.
Use wood or poly cutting boards as marble, glass or ceramic boards will dull the knife edge.
If you have wooden handled knives, apply some oil to the handle every so often. Make sure you don't allow these knives to soak in the sink or remain wet for long periods.
Whatever knives you work with, you will ensure their life and their usability if you look after them and keep them sharp.