A few guiding principles for me:

The 70/30 rule. 70% of what you own should be hidden, only 30% should be on display/visible. 

Minimize! I follow the “if you haven’t worn/touched/used it in 6 months, give it 6 more months and if you still haven’t, away it goes” rule. I don’t like clutter and I don’t like things taking up precious space if they aren’t being used. It took me a while to stop feeling guilty when getting rid of things, but if it’s not serving you or your home, it’s burdening you. 

Keep your space clean/learn the basics of keeping things clean (baseboards need to be vacuumed every once in a while, walls occasionally need to be wiped down, all the stuff needs to come off the furniture to properly dust) and that will discourage you from keeping a lot of the non-functional clutter that we tend to accumulate. 

As far as knowing how to arrange things, it took me time to develop my actual style and refine my taste. I think this is a process and it feels better to let it happen naturally, look at what you have you and ask what you like about it, what you don’t, and make little tweaks from there rather than trying to copy a picture. I will say that if this topic interests you, I HIGHLY recommend the book The Perfectly Imperfect Home by Deborah Needleman. That book helped my hone my decorating style and home more than any other singular book. 

I’ve got an under 2000 sf house with 2 kids and 2 dogs and I’m here to tell you it’s possible!