>>3124251>real >the most flatteringThe two don't always go together, keep that in mind
But as for looking the most "natural" it's more about the distance between you and the subject than the focal length. Your model will look the same taken with a 16mm @ 7 feet as with a 70mm @ 7 feet, the only difference being how much they fill the frame.
I could give you suggestions as to what combination of distance and focal length will work for any specific look you're trying to get or scenario you might find yourself in, but the only way you'll actually learn anything is to go out, experiment, and see what works for you.
>>3124253I know right? How dare he ask for help on /p/, everyone knows this board is just for gearfagging