I need help to climb Everest (100 level design)

Hi all,
After spending years it is great to feel that I have enough knowledge to finish my indie game as a Programmer at last.
However, now I have another big mountain before me to climb.

Without an artistic talent and sight I need to design beautiful levels for my tower defense game. as the one looks like below.

Is there any way that can ease the pain?

Thanks.

Btw forexample I already have this package and it looks beautiful as is. But when I start to change it, amateur touches reveal themselves. Which I don't like, and hiring a professional is not an option for me now.