Hello @brohawx , thank you very much for your suggestions. This information is very important to me, and I am eager to learn more to make myself better.
At that time, I was desire to improve myself, so after I asked the question, I used the money I saved to buy a course that taught basic perspective and structure. Now the course is over. I am currently a freelancer, but the case will end this mouth.
I used the knowledge I learned to make new portfolio. I hope that I can successfully apply for a job after the case end.
From my observation, many English turorial resources are free (such as many videos on Yourube), even if need to pay, the price is cheap and the quality is good.
The reason why I ask questions is because the related courses I looked for are very expensive , about 50,000~100,000 NTD (about 1800~3600 USD), six-month course. I can't afford it, so I want to come here to ask if there are ways or resources for self-study.
So I really thank you for providing me with the information!