Checklist for Recording and Exporting by Tejas Narayan, Arbitrandom Studio
There tends to be three main problems with the quality of the recordings. Room Tone/Noise, Distortion and Proximity Effect. Attached document gives basic guidelines on how to avoid these problems. Have a read through it, it covers all the basic issues with common problems and things to watch out for during a recording.
Before recording a project, it would be very helpful if you could make a list of the gear available to each participant (Mics/Room size/Software,etc). If possible a sample recording by each participant would also be helpful.
Make sure that the backing track that is given to each singer has no mistakes regarding arrangement. Once all the singer have recorded their parts, all the files need to be placed in an audio software and checked for any alignment/timing issues . If any editing needs to be done after the recording but before professional mixing, please make sure there is ample space on the left and right of every audio clip so that nothing gets chopped off. The rest is in the checklist document.