Every place that you record is different!
Make sure you know your recording space. Most recording studios have some form of sound-proofing, but this may be out of the question in a school or at home.
Why does the space matter?
When sound is made, it gets reflected off surfaces. Some surfaces reflect more sound than others. For example, a solid brick wall will reflect more sound than a carpeted wall. Sometimes, additions on the wall can help minimise the amount of reflected sound, such as putting up egg cartons, soundproofing foam or even a blanket. Sound also travels through solid surfaces STRONGER than it would through the air. If you have seen a live band perform, sometimes their amps may be elevated - this is to limit the amount of sound travelling through the floor - especially unwanted bass frequencies which can make the mix sound "Muddy." A way to minimise the amount of floor sound is to put foam or a blanket down, or elevate the sound source.
Ok, cool. But what do I do with this knowledge?
Knowing that microphones (especially condenser microphones used for voices and delicate acoustic sounds) are quite sensitive, you may need to alter your studio space before recording in it. Cheap, easy solutions would be to put carpet/blanket down on the floor, and pop some foam on the walls to deaden the reflection. A simple way to make a makeshift vocal or instrument recording booth is to arrange some tall structures (mirrors, clotheslines, a table on it's side, etc) in to a box-shape and clasp/tape blankets to the inside - creating a fairly un-reflective sound surface.
Speakers - are they affected?
Yes. Speakers are also affected by the various areas of the studio. The easiest way to assist the speaker in having a clearer sound is to place foam (even the packaging Styrofoam that the speakers come in) underneath them, or place them on a speaker stand. This allows for less bass to travel through the floor or your desk and give you a more even frequency response.
All of these tips contribute to having a better quality recording as well as a better quality mix.