Your labeling techniques are correct. Which ever direction you go, when given in the question is a quadrilateral ABCD, then you have to label the corners of the quadrilateral in the exact cyclic order and not haphazardly like some

B A or C A

D C B D

Make sure you draw some lines that connect those corners, your drawing will be much more realistic to represent a quadrilateral and will help you quickly recognize the internal angles faster. And thus coming to angles, Angle BCD is the internal angle of the quadrilateral, and prefer to write the number of degrees inside the quadrilateral. You might as well draw a tiny arc around the angle, inside the quadrilateral, connecting BC and CD. When you'd like to represent two such angles to hold same values, you can also draw concurrent arcs as explained above near the two angles that are supposedly equal.

Hope that helps with your question.

_________________

I am AWESOME and it's gonna be LEGENDARY!!!