Whenever someone asks me what they need to know in order to go into design, I always give the same answer.
You need to be able to draw.
You don’t need to be Leonardo, God knows I’m not, you just need to be able to move a marker over a sheet of A4. Because if you can’t then you won’t be able to abstract your ideas away from the medium you will have to realise them in. And you will become a slave of the medium rather than its master, starting from a point of limitation rather than an area of potential.