The most vital part of the recording process deals with the source material, or the singer's voice. It's important that the vocalist shows up for a recording with her voice and lyrics prepped and rehearsed. She should have plenty of water nearby during the recording process to keep her throat hydrated. Ideally, there is time for the singer to warm up her voice, particularly if she is recording a song with a wide range of notes. Experienced recording artists will have good microphone technique and know how close to be to the mic, but if you are newer on the mic or a producer who wants the best sound, be prepared for some coaching on this aspect. Generally, you want to be 1 to 2 inches from the microphone and have minimal movement during vocal delivery, but this varies from performer to performer. The ideal positioning in the booth should be made clear between the sound engineer and the vocalist early during the recording session.
When it comes to recording, the microphone is the central tool and is supported by the soundboard settings and other devices in the recording booth. Use a quality microphone with a pop screen for recording and set the input levels for the voice that you are working with. For example, a stronger, more dynamic voice requires a lower input level than a performer with a softer voice, who will need the microphone sensitivity dialed up to get the same level of audio recording. How the singer hears herself is also important, as rich sound in her headphones will allow her to sing more confidently and result in better vocals to track.
Many recordings use repetitious sounds, whether to emphasize the chorus or hook of a song or just to have a voice appear to boom like the voice of a deity. Double-tracking is a technique used to achieve these results and can be done completely as part of post-processing or as part of the live recording. Ultimately it is a personal choice on how to achieve this effect for the sound you want. However, it's preferable if you can get a vocalist to deliver lines or lyrics over an original recording, so you can decide whether or not to use the track in post-production. The audible difference between double-tracking two live recordings versus doubling-up on the same recording may be more noticeable for some than others, but live recordings are decidedly more authentic.
There are a variety of effects you can use after the audio is in your system. Depending on your audio software, these effects have varying levels of sophistication, but even on high-end decks, less is more. In general, you want the most pleasing sound possible, and that means the more natural, the better. For example, use EQ or equalizing controls sparingly and don't remove natural voice noise from the recording, such as the breath before or after a word.