OK, I'm trying to master pixel art quite long now but i think i don't get better!

So i need some help, cause it's like everyone in here makes his arts so easy. But my great problems are the things you need to master and they are:
1 - My first GREATEST problem is making shapes, i just can't so i would like to know how others do it
2 - Colouring. I can pick the colours but the result is rubbish.

Here's some more explaining picture from an banana which i screwed up very fast after i started(i made worser things btw):

Can anyone help me making me an better artist?
