I made this GFX because I was bored, and I would like to know your opinions about it!
What I was trying to achieve with this GFX its to make it simple and enjoyable to look at.
Tell me if it needs something else or if it’s okay.
If you want me to make you a GFX remember to DM me on discord (Apexodes#4399) or message me on twitter (https://twitter.com/apexogfx) and check out my portfolio for more info (Apexodes's Portfolio. GFX artist)
It is very bland. Instead of adding an stroke for example, use a white lightsaber effect.
For the lightning, it’s very unrealistic. It has no source of light.
The background doesn’t blend in with the avatar at all and there’s a strange dent in the right arm of the avatar, for the rest it’s a nice render for a begin but could be improved. I also recommend adding effects such as hexagons, fog, hacker-palettes etc.
Thank you for your answer! I’ll try to improve. 
Change the outline color to white and you could try using a crumpled paper background with a blue or pink color and try making the girl wave or jump. You could also add trees in the background but make sure the trees colors are pink. Overall it looks pretty nice!
Thank you for your opinion
Graphics like these are ordinary and run-of-the-mill. You see these types of designs everywhere in the community— especially in restaurant chains such as Soro’s— and are cliché. Designs with character renders should be thoughtfully crafted, every detail being intentional and creative. If you render a character, for example, be thoughtful enough to do a render that demonstrates dexterity. Take a look at this Phantom Forces thumbnail:
These are the types of renders you should be creating. If you can’t create these types, try and learn how. The design you created reflects the common graphic trends in franchises and companies you see on Roblox as mentioned. From the picture above, compare and contrast:
See the differences? The former reflects strong dexterity, and the latter, weak. The latter reflects cheap, quick-to-make designs that are unoriginal. By creating renders like theirs, you are giving off impressions that your designs are typical and lack originality and hard work. The impression you give off with the design is incredibly important. You are creating the “franchise vibe,” if you will, and that is something to avoid if you are not doing anything franchise-related. If you are doing these renders for franchise groups, do not “assimilate” into their design style, because you will not stand out, and you will be seen as a knock-off of every other franchise group that exists on Roblox: Soro’s, Hilton Hotels, etc.
Hopefully this helps! 
Excellent points, I’d like to add on to what you said.
The Phantom Forces image you posted is good, but I believe even it does not demonstrate the potential of properly rendering characters, creating a coherent scene and a detailed image.
I like this one more. The one you posted is great, however the characters almost look floating, unattached to their environment. I particularly like the one I posted above because it clearly looks like they are somewhere (near some buildings). I love how this artist manipulated the background and also used similur effects on the character to create a more interesting look for the viewer to notice.
In conclusion, I very much agree with @v_e, I don’t believe it could have been put in any better of an explanation. I hope this post adds on the original explanation.
Yes, all of these are excellent examples. I chose the one picture since it emphasizes fantastic lighting manipulation, the key distinguishing factor between the Phantom Forces’ thumbnail and the others.
The ones you added work as well— your post does add on to the original explanation nicely. 
Try to change render’s stroke color. Or better change the stoke on outer glow or strips, which will separate the render. Background shall be a bit darken or render shall be a bit lighter. But totally looks good
