Welcome to Just Answer and thanks for your question. First, it is best to start out with good quality knives. Cheap metal will not hold an edge. After sharpening thoroughly, store your knives in a holder in a drawer, or in a knife block between uses so the blade doesn't hit against anything else and dull it. Of course, I'm sure you wash a knife immediately after use, dry it completely and return it to its storage place. You should also straighten/gently realign the edge with a steel every week or so to maintain it between full sharpenings. Your cutting board also matters. While you can't damage marble or granite, a plain wooden (maple, bamboo) doesn't dull a knife as badly as harder materials.
Could you explain what you mean by "straighten/gently realign the edge with a steel?"
You've probably seen chefs on TV and father at Thanksgiving dinner using a honing/sharpening steel. There is a little video in the link below. You just gently draw the blade down the steel a couple of times on each side. While holding the steel in the air and flapping your arms like a chicken perhaps may make someone think they look more "professional," the best method is to put the pointed end of the steel on your cutting board, holding the steel perpendicular to the board and draw the knife blade gently down each side. You can control the angle that way so that each side gets the same amount of aligning. You won't look like Wolfgang Puck, but you won't ruin your knife either.