The Microphone Doesn’t Lie
Not only do microphones never lie, they often exaggerate the truth.
Please excuse my misuse of the phrase; I mean to say that what a microphone hears often sounds like a hyperbole of the source. Mistakes are painfully apparent and stellar performances sound impossible.
It’s for this reason that the recording artist be fully prepared for the session. Their instrument should be in top shape and the chops required for the song should be well-toned.
Change your strings/heads/reeds/etc. a day or two before your session and break them in. Not so much that you take away that glistening new-ness, but rather just enough that you know you can rely on them during the session.
Rehearse the songs to memory well before the session. You want to come in fresh to it, but ready to play every note correctly. If you are a professionally trained musician this may not be necessary - a quick run-through a chart may be all the rehearsal you need to give an optimal performance.
If you’ve never recorded before, try it before you spend much money or someone else’s time. Most computers today have a mic line-in and most laptops even have microphones built in. You won’t get the best quality, but you will get comfortable performing for the most discerning of audiences: yourself.
The microphone doesn’t lie. Audio engineers can coax them into telling the nicest version of a story, but it’s impossible to make love out of war.