I love vocaloid and I have seen this stock before ( you might have used a render but I know the image) it is already lq but imo that doesn't mean that it should never be used !!!

I think you have some good lighting an some decent effects going on behind her, love how the hair was used for foreground rather than a bunch of c4d, it's a trick I myself use to make the piece more clean looking,

I would suggest that you play with brightness/contrast a little more and use a photo filter of some warming/wooling to bring out more colours from the actual render, as well once all done another thittle trick I use when it comes to anime is put a vibrance on an just touch it up a little to make the colours more pow

Not every ones choice or style, but I thought I'd just throw in a couple ideas

Good stuff anttie , keep it up <3