Okay, so here's possible tactic #1:
use images that are already on imgflip as templates.
I noticed the "C" one was featured with the option next to it to 'Re-caption this meme.' That means that you either checked the box to make it publically available when you uploaded it, or it was an image you found on imgflip. Whereas this one, the Dee Snider one, and the Eazy E one don't have that option, which means (I think) they were images you uploaded, rather than finding them on the site.
The images that are on imgflip usually feature much quicker, and seem to get less "mod review" than images you upload. And I'm thinking that the more mod review a meme like this has, the more chance a mod might think, "This is just a prank, or spam" and not approve it for featuring.
So that's possible tactic #1. Try to use templates that are already on imgflip.
They're likely to get less mod review (notice my number memes are mostly on popular templates), and therefore much more chance that they'll just get an automatic approval. Does that make sense?