[JeffreyKaine]

This is going to seem overly simplistic, but... Practice!

1) Find designs that you love, copy them pixel for pixel

2) Start mixing and matching elements from different interfaces that you find.

3) You'll start to see repeated patterns, get good at connecting these patterns together into new interfaces.

4) After a while of this, you'll see that you don't need to do as much research and direct copying anymore.

5) Congrats! You are a junior designer, keep practicing :)

[liampronan]

This is the same advice I was going to give and is how I've been working on my design skills.

One addition: you should look through Dribbble [0] or similar sites for inspiration, and you can use pre-existing resources for Sketch or Photoshop [1] to build mock-ups. I find it better to improve on design by iterating a bunch on mock-ups before working in HTML/CSS/iOS (since I'm much more familiar with going from design mockup -> front-end).

0 - https://dribbble.com/search?q=website 1 - e.g., http://www.sketchappsources.com/