Make sure you know the context when using the word qualify. In one sense, it means to be right for, to measure up. In another sense, though, qualify means to change something slightly, to limit it or add a condition to it.
If you want to qualify for your driver's license, remember not to drive through that final stop sign without stopping. I guarantee you that if you don't stop you will not qualify. You don't just get your Eagle Badge. You have to qualify for it—there's a lot to do before you get it. The word might be used in its other sense like this: If you plan to get married, keep your vows simple: say "I do." Don't qualify them by saying something like "I do...except sometimes, when I don't." If you have to qualify your wedding vows, don't get married.