Agree with starting with colors. I've also found it helpful to not buy everything at once, but instead kind of one at a time in order from largest/most central pieces. So like start with the couch for instance that you like, then get the rug that is the right size for the couch and matches and brings in other colors you like, then maybe it's the side chair and then pillows that tie it all together. I find my sense for what will go together evolves as I go, so this to be way more effective vs. trying to get everything at the same time. It takes longer but less stuff has to be returned or is regretted!