Well...
I wait to be all alone at home because after I'd go too shy and I'd be either barely understandable (like weak) nor making supra-breathy-files.... and eventually getting my voice cracking up and me being mad and down orz
Generally I wait having my voice enough powerful nor sounding normal to do it (because it sounds scratchy nor the voicerange is pretty darn limited OTL)
If the voicebank needs a high-pitched voice, I simply usemy high range... I noticed if I eat cold/sweet things (especially dairy products like ice-creams), drink cold drinks nor even breathing cold air, strangely it'll help even more
If the voicebank needs though a low or harsh voice, rather spicy food, hot drinks and warm air (or simply recording in the morning if I'm alone lol)
After about voiceacting, I try to act like if I was the character itself (so the immersion makes the voicebank easier to produce)
And a stuff I do when a voice is hard to produce or that I really want to keep the same tone (because I cannot record all in one take due to lack of time or sickness), I play voer and over a sample (generally the "A" but it can be another sound, it depends of the one I do -like if I need to finish a T class, I'll play the "ta") and once I feel I manage to reproduce the tone while singing along with it, I quickly launch recording and I record
And finally, doing some breaks in the case the recording sessions are supra-long, and of course stopping it if my voice suddenly cracks up and that I cannot go back the tone I'm making
I think that's all...