Present the kit and the way you built it as it is. Let the build speak for itself. Use better lights, a better camera, a good backdrop, a good pose. If you want to depict your build with it glowing, flaming, smoking, melting... do so with practical effects and tools. Create those physical effects with real tools and incorporate those into your build.

If you have to resort to digital enhancements with the aid of a computer to make your post submission look good... we have /r/gundam where you can post such content and where it will be gladly accepted.

Even black and white photos are a disservice to the build. How can we tell if you've properly or cleanly painted a kit if you depict the whole thing in black and white? Yes it is artsy... but it's not helping us know more about the way you build. Again, if you want to express yourself in that manner, /r/gundam is a venue for that.