Responsive Site For Product Preview

Hi there everyone! It's me again :) I'm with you with another challenge. I started from scratch and tried to challenge myself each day. Anyway, here's my question for you all coders. How to get better at using media queries? Any ideas about that? And my other question is that in CSS, everyone has their own unique style, but how do you keep your codes clean and short? I'm using a lot of code but realize there's a much easier way to do it. So it kind of break my heart :( Thanks all for your answers, and happy coding to all! ^^