Its best to post your artwork at the original size, so 1 pixel stays on pixel if that makes sense.
one of the main things that feel wrong is the pose, it feels like the goblin would fall over.
Put the legs apart a bit, and position the arms in a more interesting way.
I think your goblin just needs some more work put into it.
Use the tutorial only as a starting point, then add more things like :
- weapons
- armor
- mouth
- colors
- background
Googling goblins and orcs should get you some inspiration
good luck ! : )