Hey, what exactly are you trying to make? If it doesn't look realistic because the colours lack harmony then you should spend some time researching on colours. Everything you can find on the topic. Examples of how other people use colours and just research.
I'd suggest you get Adobe Illustrator if you're using Adobe software. Photoshop has it's uses but for UIs and designing is always best to start with Illustrator since it's easier to work with shapes and everything is vector.
If there's anything I can do to help you out let me know!
Yes I use Adobe Illustrator CS 6! I really love it but when it comes to colors and how to make shades and effects I suck at it! I use like one color or white with color gradient only and a shade using an object and create it by pathfinder.
I have saw a tutorial and they call what I'm talking about is Depth. How do you create depth? thank you.