The most honest answer is you don't. Unless you are a legit genius-level developer, in which case you wouldn't be posting this question on here.
I'm 19 with no formal qualifications except high school. Not a 'genius'.
There are jobs out there for young developers!
I wouldn't trust most working developers I've worked with to be able to deliver me something decent from start to finish, alone.
That's why companies have BAs, managers, testers, etc. Because doing it solo is a rare feat, unless we're talking gluing a wordpress theme together, in which case I'd recommend they look into squarespace :)
I wouldn't trust most working developers I've worked with to be able to deliver me something decent from start to finish, alone.
I have the same feeling for a lot of my CS university peers but yeah like you implied being on its own is a different situation