Practice, then practice some more.
Pick something you can build and work through the problems and you will learn as you go.
Do not get discouraged, no one started great, every one of use started somewhere and we are on a journey to where we end up.
You will look back on things you design today and laugh at how you made it, but we ALL do that as we constantly learn.
Google your problem, find the YouTube video where someone walks you through it and do it a few times.
You will progress faster than you think.
I always found that having a project is far better than following simple things. A project focuses you on the tasks required to solve it.
I did the same thing each time I learned a new programming language and then 3D design.
Be realistic, try to match the project to new skills you can learn, but make it practical.
The first model I created was to be used in my conservatory to replace an air vent where plastic had petrified over time. The new one works well, I printed six, three to install and three spare.
I shared it here and despite it being a specific set of dimensions, many have downloaded it.
This is something you need to enjoy, so keep thinking positively.
Your friends and family will soon start asking you to solve problems for them.
I have created cogs for an industrial ice cream machine, drain covers to stop a blind dog from falling into it, an extension to a portable air conditioner so it could be mounted into a window securely. I haven’t shared any of those as they were very specific for friends.
I began my 3D designing journey at the start of 2024 and I have shared over 850 models on MakerWorld with another 20 queued up to share when I am able.
I had zero 3D design experience when I started and had no training.