Yeah, it takes practice to get a professional sounding recording. But if you work hard enough at it, you'll do good. Two more pieces of advice. Find a mic with a good, mellow sound to it. Avoid anything that gives your voice that "tinny" sound, or any kind of echo. Second, use a mic that has a foam cover. It reduces the "puff" sounds you get when you're speaking. A good mike with both a cover and a silk wind screen will get rid of it all.
If you want to add a bit more professional spin to your recording, I recommend adding a pop screen to your mic. (example
) If you look at the example image, you'll notice a circular black disk in front of the mic. That's a pop filter. It's used to stop the popping noise created when you speak. The foam cover helps stabilize and soften the sound picked up by the mic, but the pop filter gets the really noticeable stuff. You can get a cheap one over at Amazon here
. Ideally you want that about an inch or inch and a half from the mic. Then when you record, put your lips about an inch away from it and speak normally. It might take a little getting used to at first, but once you're comfortable with it, you'll have less post editing to do on each recording.