This is a huge topic to say the least ;-)
There is a major difference in audio techniques for recording vs audio for sound reinforcement.
The most obvious is that for recording you only get to keep and manipulate later what you have recorded, and in a fashion that you have some degree of isolation from the multiple tracks to later work with.
Basically, there are two different methods, one is where the sound is recorded on a separate device, the other is where you record the sound on the same camera. Each has its pros and cons, but the simplest is to have the sound recorded on the camera.
A lot depends on the camera you are working with, if you are more on the consumer end of things you will want to get a simple controller for the mics usually from a company like Beachtek, that allows you to have the mics, provide
phantom power, but still feed the output to the camera. Most consumer cameras only support
mic level in, not
line level in unless you get up to the more semi pro like the CANON XL SERIES.
So get a good mic and
boom, I personally like the
Sennheiser K6/me66, but with a Rycote blimp and wind
shield and
boom pole, Gitzo for instance. If you only need these items for a short time the are available to rent, usually the more professional
Sennheiser 416 is the industry standard.
Get a very good pair of isolated
headphones, so you are SURE you have recorded what you want and NOT part of what you want reinforcing the location sound.
Working a
boom pole is a lot of work, it is heavy, and muscle building over time, you typically work with the
boom/mic just out of the picture either from above, or from below, depending on the shot.
The other method is with an independent recording
system. Here the issue comes down to syncing the recording to the video. At the end of the day, the most reliable method is the old slate, which you shoot and clap so that you have both a visual and audio
cue to sync up in final production. Key to making this easy is to still use your on camera mic so that you have a guide
track that you then in the NLE
system you can
line up the two sources The complexities of timecode syncing
etc in most cases are not worth the effort since you have good flexibility in the NLE and
lining up the waveforms for the clap is pretty easy.
My assumption is that your friend is working in video. IF it is in film then things get a lot more complicated, since you definitely record audio independantly, but also typically you need to get into ADR dialog replacement, since in a lot of cases the film camera is simply to noisy for you to be able to film and audio record at the same time.
Make sure that for each scene in addition to dialog you get some wild sound and location sound that you can use for editing
etc.
It is a lot of fun, but takes a different mind set.
Sharyn