Another way of saying this... audio is king! I can’t emphasize enough recording great sound is essential. Invest in a good audio recorder and plug microphones directly into that. A device like a Zoom H4N is a great dedicated audio recorder. Until DSLR camera manufacturers are will to raise the cost of camera bodies to cover real audio inputs (like XLR connections) you’ll still need to go this route.
Syncing up sound is simple if you use a clapboard (a large spike appears on both the camera audio and the synced sound). You can also use tools like Plural Eyes (available for Final Cut Pro, Sony Vegas, and soon Premiere Pro).
One more important piece of audio advice. Once you’ve edited your video rough cut... close your eyes and just listen to the edit. You should be engaged in the story without the use of visuals or transitions. A good edit works as a solid radio piece... adding pictures and graphics will only make it better.