I used to edit almost all my old pictures, but as I've learned more tricks I've found that it's often unnecessary. My first attempt at Obi-Wan from The Phantom Menace
was edited by cutting-and-pasting in MS Paint:
Then I had another go a couple of years later and found that I could make a much
more realistic likeness without any editing at all:
There are literally hundreds of useful little tricks that you can pick up - for example, with your Storm picture you could make the X logo using text and a circular earring, and white-out her eyes using little white beards or something like that. Obviously the logo wouldn't look quite as neat as it does here, and you wanted to use a different background - but it's something to bear in mind if you're entering contests where editing isn't allowed. It's mostly a matter of experimenting and trial-and-error. And having lots of patience helps.