What are some of the things you consider when thinking about visual design? 

For me personally, I usually I try to imagine a few seconds of the game running in as much detail as possible- imagining the buttons you press, how the characters respond, how the camera moves, etc etc. Then I try to break that down into its individual aspects (like below).

• perspective (top down, profile, 3rd person, 1st person, etc), whether to use a perspective/orthographic camera,
• how simple/complex the shapes are,
• color choice (warm/cold, vibrant/muted, dark/light)
• lighting/no lighting
• how stiff/fluid the movement should "feel" (this is more of a gameplay design consideration, but I tend to think about them in tandem)

 From there, I try to make a basic scene, working from the easiest to implement to hardest to implement. Usually in the middle I'll do some gameplay programming to make sure the aesthetic fits the "feeling" of the game, and to make sure the mechanics I have in mind are feasible. If not, I'll go back and reimagine the game without the scrapped mechanics

But every time, it doesn't quite feel right. I never can quite get it to look and feel how I want (or even get close, for that matter). Is it a matter of experience? Or am I approaching visual design from the wrong angle?

In my last game jam, I was really happy with how it ended up looking visually. Nothing we did was technically very challenging, but the choices we made worked well. Most of that is thanks to my partner, he came up with and implemented a ton of the ideas that I didn't know how to do at the time (or even know were possible, he worked some magic on the lighting and color grading). I hope this time I can make this game look good too.