There are many polysemy phenomena in translation, so you should understand these knowledge. You can browse some websites in pure English, or the top 500 English websites in the world to increase your knowledge. Doing English translation is still very important for mastering Chinese, so Chinese should be excellent. I'm not sure about the course, but I think it's useful to watch the original English movies, at least I think it's useful.
As a part-time translator, you can submit your resume online. I am recruiting in Zhilian, and I often see such recruitment information on the Internet. You can try to register an account. Of course, people's requirements are higher.
That's all I know so far. I hope I can help you a little. Start (a disease)