There are questions I keep instinctively in my mind when I draw my characters
-What are the shapes of every body part?
-how does the faces/eyes/nose/mouth/arms/legs' shape look like?
-are they long? short? pointy? squarish? round?
-are they straight? curvy?
-how steep are the angles?
-are they thin or wide?
-How far apart each body parts are from each other?
-does the gap between the eyes near or far? etc
What are each of the parts sizes in relation to each other?
-is the eyes bigger than the nose? etc.
-is the head bigger than the body
-how many heads does the entire body measure up?
-does the hand cover up the entire face?
Believe it or not characters has their own sets of shapes and measurements and that what's make them who they are. Any slight adjustments can cause the character to go "off-model" I did a short overview about this right here.
I don't use character sheets for my OCs because I already memorized them but if it's someone unfamiliar I'd totally wanna have them around just so I can answer all these questions.
That's just me anyway, don't mind me. I'm just gonna crawl back into my hole.