Sound field matters. When doing location recording, be careful and listen to the environment you are in. Obviously, things like fans, air-conditioning and else matter, the quieter the place the better it is for your recording, But also the room acoustics matters, a lot. The echoes and the reverberation of the place all will be imprinted on your recording and then super imposed to the room acoustics where your final production will be played in. If in a headset or a professional cinema theatre you are in luck because not much room acoustic will be shown on the playback side. But obviously this is not always the case, so the quieter the better.
Making sure your microphones are as close as possible to the source (a voice for example) is a must, particularly if you are in a regular room with no particular acoustical treatment (i.e. most rooms on earth). On location you may not notice the issues, but once in a different place it will become obvious, see eventually annoying depending on the original recording.
The specifications of your microphone will matter too, particularly in a difficult acoustical context. Having a lavalier microphone could be a must, however sometimes shotgun mic are desirable. As a rule of thumb, the longer the mic, the farther it will reach in a straight line and the more it will cancel on the sides and rear. So aimed straight at the mouth of the speaker from right above the top of the image frame is what you want to look for. The closer to the speaker’s mouth the better. Ambiant sounds of the room will be reduced while voice will be emphasised.
Microphones directivity is described in terms of pattern, or shape. Starting with the self describing Omnidirectional, shape then respectively are cardioid, hypercardioïd and shotgun. Something like an AT4053b is a good example of an allrounder that will do good in a roomy ambiance, while at the same time keeping a reasonable size and price. This is an hypercardioid mic, so you will find similar offers with similarly excellent performances, less or more expensive, from other manufacturers, such as, Shoeps, Sennheiser or Rode.
However, we tend to prefer a good quality lavalier, headset or even handheld microphone. These too can be found with specific directivity patterns.
A good quality omni mic can be useful for outside ambiance recordings, but for voice, you want to have a quality lavalier mic, ideally cardioid, for these DPA 4080 or Sennheiser Mke2 come to mind. Plan for more or less 500 USD investment for one of these. (Or better 1k for two, as you want to have at least one spare…)
Then, finally there will be the question of transmitting the signal. So while a (balanced) cable is the safe way to go every-time you can, sometimes it is a not possible. Therefore wireless transmission is in the air (no pun intended).
Please check here for more about audio for video recording
More on microphones polar pattern can be found here on Wikipedia.