1. First, choose appropriate mechanical drawing textbooks (such as non-mechanical textbooks, don't choose), and it is best to choose a publication date that is close to now, because the mechanical drawing standards will change; It is not enough to watch some teaching videos or animations without teaching materials. I often go to Chengdu Aviation Vocational and Technical College to watch their teaching animations. Personally, it's not bad. You can have a look.

2. Buy some necessary tools, such as compasses and triangles, and it is best to buy some plasticine to strengthen the imagination of space.

3. Always look for some 2D pictures, and try to imagine the shape of the stereoscopic picture. After a long time, your painting will be greatly improved.

4. A point that is often overlooked by everyone: dimensioning. Don't underestimate dimensioning, it reflects a person's drawing level, drawing ideas and mastery of drawing standards. I met many colleagues or friends at work, boasting about how well I learned painting, but I could find some difficult products for him, all of which were labeled as messy.

As for mathematics, don't worry about it. To tell the truth, my math level is only junior high school, not even senior one. Can't learn to draw as usual, and still do your job well?

I hope my answer is useful to you.