A visually pretty video with bad audio, is just a bad video. Here are a few tips to make sure your audio sounds A+.
1. Quiet Room - listen to your surroundings, is there a vent that comes on and off? Do you hear any electronics or lights? If so, either turn it off or avoid the room. The buzzing, humming, wooshing will likely come through and distract your audience.
2. Soft Room - Avoid rooms with lots of cement and hard surfaces. Even lots of desks can cause bad audio. Look for carpet, ceiling tiles, and sound dampening fabric on the walls. Less hard surface = clean audio with no echo.
3. Test Before you shoot - take some test recordings. Bring headphones and listen to the playback. If it doesn't sound right, figure out why and change it. You might have to change rooms, or just adjust the microphones direction a little.
4. Two mics are better than one. Plug in your main recording microphone into the digital voice recorder, there can be a big difference between the quality of audio recording tech in a camera and in a standalone digital recorder. Use the recorder to store the audio and sync it to your video later. That's one of the reason people use the marker cards in movie product.
Music adds pace, and excitement to your video, keeping viewers involved longer. Besides quality of your song, and fit to your video, you need to be careful to choose music that is not copyrighted. Songs like "Call Me Maybe" or "Hotline Bling" are fun and exciting, but it is against the law to use them for your own use. Some songs are copyright free or have use agreements which allow us to use them in class or for non-profitable videos. Resources with songs like this are: