The recording environment - If you are intending to record at home you will need to set aside a room where you can do this without creating a disturbance to your neighbours and also prevent outside sounds such as traffic and barking dogs from finding their way into your microphones and into your recording.This will be less of a problem if you live in a quiet area in the country for example, but for many of us living in and around cities noise is a real issue (particularly if we are either creating it or needing a super quiet environment to record). Condensor microphones for example are incredibly sensitive and will pick up outside noise easily. Sound proofing your room can be done fairly cheaply using materials commonly found at a hardware store - in fact there is an excellent sound proofing guide available online which shows you how to do it. (and no, a whole heap of mattresses will not block the sound). Internal acoustics - Not only does your room need to control sound going in and out but it also needs to have minimum echo which will make it much easier to hear your recordings and make the adjustments without sound bouncing around walls and ceilings and giving you a very different result than what you need to hear. Perhaps the simplest solution here is to hang some heavy drapes on opposite walls and make sure you have carpeting on the floor. Also while we are on the subject of noise it will be most likely your computer will be creating some from the fan in the power supply. What you can do is put your computer in a closet or divide off part of your room with a partition between your computer and where your microphone is - that will help reduce unwanted noise getting into your recording via the microphone.
Recording music.