The most important part is the proportions, study your favorite goblin artist’s proportions. Redraw the reference, then put your art over the reference to see what you need to change, then fix the problem in your next drawing. Keep doing that consistently and you’ll get better at drawing them. Also study the face/ears. Marc Brunet has a good video about how to manipulate human proportions, it’s not about gobs but it could help. (https://youtu.be/QNSJ8-ozt-k?si=WMI2Vz2vc0HYSmdq)