Make sure that your first story matches your ability to write it. Aka: don't bite off more than you can chew, with it.
My advice is to start of with something that isn't too complicated, that has a small cast, or that loosely follows a tried structure or genre. Avoid a grand scale fantasy story, with dozens of plot threads and character perspectives, as this can easily be overwhelming.
That doesn't necessarily mean that your first story can't be emotionally complex or, thought provoking, just something that matches your level of experience.
I say this from my own personal experience, as I chose to make my first published comic be a time travel Sci-Fi with a believable set of rules.
Only after two years have I finally managed to polish most of the time travel related plot holes, and only then with the help of an experienced editor and writing tips from my artist.
I hope that helps in your creative projects,
-Pablo, Author of INTERMINUTE