When it comes to creativity its important to gain a strng level of confidence, just keep singing along to your favorite songs as you strum the chords in a rather simple progression, (sooner or later everything should come into focus.) During your warm up sessions, start out with something very simple, try singing along with the notes you are playing, also try singing any pitch that comes to you and playing it back on guitar. Which will help you develop a good sense of what you like, and what you're comfortable with.

-Joseph, :).