Microphone Selection
There is a lot of material written about microphone selection. In particular check Shure microphone Educational Publications.

I have only included the most common options here.

Microphone Type:  The most common mic types are dynamic and condenser.  Dynamic mics tend to be less expensive and more durable than Condenser mics.  The trade-off is they typically don’t sound as good.  Condenser mics are prone to moisture damage, physical damage, and require a power supply (usually phantom power).    Both work well in different situations.

Microphone Pattern:  There are three basic microphone patterns – Omnidirectional, Cardioid, and hyper-cardioid.

Ominidirectional picks up sound from everywhere around it regardless of where it is pointed.  These are quite good for choirs and public speakers.

Cardioid mics are the standard stage mic.  They pick up in the direction they are pointed and DON’T pick up in the opposite direction.  A vocalist on stage points the microphone at themselves and away from the stage monitor and magic happens.

Hypercardioid mics pick up even less on the side.  The drawback is they begin to pick up directly behind them.  Point these mics so that they are pointed about 120 degrees away from the monitor speakers.

Frequency Response: Vocals and most instruments rarely go below 100Hz. Bass, Bass drums, low winds and piano (and pipe organ) are about the only instruments you need for low frequency. Most low instruments will just sound thin if recorded with a traditional mic lacking lower frequencies.

Vocal mics typically have some boost in the 6KHz – 8KHz region to make the voices more crisp.  Instrument mics and recording mics are more typically flat frequency response.

Microphone Position
Correct microphone position is more art than science. For the different pros and cons of mic placement I will refer you to external sources:

Bartlett Audio:  Lots of great detail on mics in different situations

Shure microphone Educational Publications.  Many documents on different techniques and applications.

Guitar Mic Example: My own demo with surprisingly dramatic results