I have a rigging problem. Whenever I rotate the bones after finished rigging, the weird model errors start appearing. Please help me out or link me to the tutorial that would teach me how to fix it. Any help would be greatly appreciated
Check if the face orientation is right. Press Alt + V and check Face Orientation.
The outer surface should be blue. It could also be a scaling problem. Your model and rig should have the scale value 1.000. To do this press Ctrl + A when object is selected and click on Scale.
Thanks everyone for the help! Actually the answer is Automatic Weights. I tried doing the Weight painting and Vertex Group myself but the results are still not so good until I tried the Automatic Weights (something I didn't know that it existed until now). So, again, thanks a lot to all of you that helped.