1, and most importantly, drawing. No matter how well you master the principles of materials, engineering and machinery, it is meaningful to express them. The way of expression is of course drawings, and the most popular software at present is of course PROE, UG and solidworks.

As for CAD, it has gradually faded out in the current non-standard design and product design industries, but it is still used.

2. Know how to choose the type. The choices here include: materials of parts, models and specifications of pneumatic and hydraulic components, bearings and other standard parts.

3, understand processing. The processability of the material determines whether your product can be realized. What kind of material can be hardened by what kind of heat treatment, etc.

4, budget control costs, these can be achieved at work.

In short, the first step you have to take is not advanced mathematics or engineering mechanics, but a stepping stone!

The stepping stone is to learn a 3D software, which can express your design intention.

Wish you success!