When locking sound to picture thats shot with a DSLR, I've had issues syncing the sound recorded on my H4n because of the poor sound quality of the onboard mic mounted on the camera. Any recommendations for the best DSLR mounted camera mic?
The Rode Video mic is a safe bet, and is fine for guide tracks, the Pro version is worth the extra money.
I would also suggest using the clapperboard at the start and end of takes, remember to hold the board upside down at the end. Having the board at the start and end allows you quickly to see if the camera compression has altered the timing.
Rode makes a stereo and a shotgun specifically for DSLRs (shoe mount, battery powered, and correct sized TRS jack). They're relatively inexpensive and light years better than what you can get with the built in camera mics (if you really want to call them that). Look for Video Mic and Stereo Video Mic. I think they both come in two SKUs now: standard and "Pro."
Another option is to buy a shoe mount to 5/8 adapter like this one. Then you can use any standard mic stand shock mount (Audio-Technica makes a pretty versatile one) to put a shotgun or other microphone. Of course, in that case you'd also want something like a Juiced Link box, to provide phantom power, preamp and impedance conversion.