try to mess with layers, edit the colours, colour level, colour temp... Add new junk, like put a pokemon in the middle of the green day concert or anything lol!
I used to play with... Wasn't photoshop back on my time, cant remember the name though, but I also had corel draw.
Ah, try looking at some guides at the internet, photoshop for example gets quite easy once you get the hang of it.
I have some examples of thing's I've done on it :P :
I used to do forum signatures like 5 years ago, so I was like.. hmmm 15. xD!
Its quite simple how fast you can do this for example:
I added the halo (?) guy, the background and I had some futuristic panel layers so I just added it, after messing with the colours I put her name in GIF using animation set-up in photoshop.
This one here was even easier, because the girl jumping was on the font I used, I just put her to jump using the frames on the animation, also 5 years old:
This one is about 2 years old, I just put here for fun, and that's what I suggest you to do, have fun making dumb stuff, mess with those layers!
This one here, I just made the colours, the drawing was empty, kinda looked great. Also 2 years old:
Another 2 years old silly edition:
And another 2 years old silly edition, but this one I did some tricks on it, like shading, putting her backstage and etc.
But you know, you don't NEED photoshop to make fun editions, I used to do silly stuff on paint as well, I remember once I did the Star Trek crew into some jap games character on photoshop, no tablet, puuure mouse :P!
So Picard can easily become a woman:
or Spock and etc.