I will give you some tips on that! I hope it helps you
To me, that's a matter of having your character's appearance fully sorted out.
First, you gotta get used to your characters. Take mental notes: character A has a pointy chin, thick eyebrows, strong build, etc. You can go further: Character A's eyebrows are the same thickness as his nostrils, silly stuff like that.
Let's take my dear Eliot from TKITS as an example.
He has a childish face, with soft curves, upturned nose, bigger eyes, proeminent eyelashes, thin eyebrows, light freckles that cover his cheeks and nose, etc. I keep those features in mind while drawing him.

Then, take a sheet and draw character A twice, on opposite sides (this way you can't look at the first attempt while drawing the second one). After you finish, compare both drawings. Are they consistent? If not, what did you miss? Which drawing is better representing character A and why?
That will make you more used to your own character. Soon it will come out easily and consistently. 