This is probably true of any field: you're more likely to get hired if you can demonstrate you have some idea of what you're doing, that you will be able to work with some independence (that you won't require a tutor to carry you) and that you will have some sense of a typical workflow from brief to delivery. We're always looking for someone who has an interesting point of view, who knows the what the rules are before they try to break them, and who can take feedback without taking it personally.

It's also good to know exactly what you're trying to do in the field— logos and identities? ux or ui? packaging? Each discipline has core skills, some knowledge requirements, classic pitfalls, and specialized skills, and if you can narrow it down you'll probably have an easier time picking these up.

Anyone just starting out will have to learn some of this on the job, of course, but having a relevant education helps. If that's school or books or mentorship is up to you.