I’m guilty of taking them too (though I don’t anymore). There’s a few things about them that I just don’t see as being fitting for a Christian. It always comes down first to motives.
Why are you taking the selfie? Are your motives pure when taking the selfie?
I come across selfies with bible verses. These are … interesting. When I think of even just the world “selfie, I think of self, not others; vanity, not holiness. So to post a Scripture along with the selfie is somewhat contradictory. Unless the selfie is just for kicks and giggles, like you wearing or doing something goofy to make the observers of the selfie laugh. I presume that’s okay, but these selfies seem more rare.
The more popular selfies are Christian girls or guys in somewhat suggestive, if not moderately suggestive, or just plain suggestive clothing (for guys it can be lack-there-of, aka a shirtless selfie flaunting toned muscles or even a girl posing in a bathing suit), or lots of makeup, or just a picture where they look attractive. The photos are alluring and often, it seems Christian selfie-takers are single (unmarried).
All-in-all, just check your motives please. If you’re posting a selfie because you think you or your body looks good and you’re seeking attention, I urge you to reconsider. If you truly believe your motives are pure, fine, but a good question to ask in sincerity is, “Will this glorify God?”