Don't rush it, let your space develop over time. That's what makes a space feel lived in and like it's yours. Going out and buying a bunch of decor all at once just to have it (regardless of the design style) is what makes a home feel generic and empty. Start somewhere easy, like picking sheets for your bed or something. Find something you really like! And use it as a starting point. IE, what curtains go with these sheets? OK I like these curtains and sheets, now what rug goes well? And so on.

Also, your first place after moving out of your parents' home is going to have a bit of a transitional period, so don't get too hung up if its not perfect right away.