Pick a project (or better yet, a problem), and make it happen. Pick an area and tinker in it.
There's not really much more to it than that.
You may need to learn a ton as you go if you don't know the basics of the area the project is in. Software based projects are probably easier than hardware based projects in the sense that you won't lose money to change your mind.
On a RPi, you can always just rewrite the SD card and carry on. No harm, no foul. You're not counting on it like you would your main machine (until you are).
There's not really much more to it than that.
You may need to learn a ton as you go if you don't know the basics of the area the project is in. Software based projects are probably easier than hardware based projects in the sense that you won't lose money to change your mind.
On a RPi, you can always just rewrite the SD card and carry on. No harm, no foul. You're not counting on it like you would your main machine (until you are).