Remember this: a cheap mic near the audio source is better than an expensive mic far away. Technique is huge. Don’t buy gear that doesn’t represent an appreciable difference in quality or convenience for your purposes.
Look at where you’re recording and listen to your environment. This is one of the number one things you can do to improve your audio but so many beginning filmmakers try to avoid doing it.
Watch out for small rooms with hard, parallel reflective surfaces. Treat the walls with acoustic blankets, furniture pads, or regular blankets.
Turn of a humming fridge and put your car keys inside.
Be cognizant of how audio’s physical needs affect blocking when planning shots. You may not always be able to put the mic where you want (e.g. boom pole shadows) but remember that the environment itself can house a “plant mic” hidden somewhere in the scene. Again, mic proximity is king.
Boom Mic Technique
Be aware of handling noise
Use the right mic for the scenario
Get the mic as close to the frame’s edge as possible
Lav Mic Technique
The lavalier mic, whether wired or wireless, is often a staple of good dialog, particularly when the mic must be “visible” in the shot. That said, there are a few things to keep in mind when using it.
If using a wireless setup, check for the most clear frequency available and monitor your audio constantly
If the mic is not to be seen, know that you’ll likely need to run in underneath clothing (this, along with the mic’ed talent’s bathroom breaks can be a bit awkward)
Use medical tape to attach the capsule to skin and double-sided tape or gaff tape to attach directly to clothing
Use moleskin to prevent friction noise as the microphone’s diaphragm rubs against clothing
Create a “loop” in the cable to prevent a sudden tug from transferring to the mic capsule
Avoid placing the capsule directly over the talent’s heart
No Shotguns Indoors
Just like you wouldn’t operate a traditional shotgun indoors, don’t try it with the microphone version. Hyper-cardioid pencil mics don’t use interference tubes and are better for small indoor spaces. A shotgun mics interference tube uses phase cancellation which creates problems with early reflections. A shotgun mic is often a hyper-cardiod pattern with the interference tube to reject off-axis and rear sounds–this makes the shotgun mic more directional.