1. Make the most of your lighting. Not only should your fixture be pretty to look at, it should cast beautiful light. This can make a room feel warm and comfortable or like a hospital.
2. Don't slack on the seating. Make sure there is plenty of comfortable seating for guests so nobody has to awkwardly sit on the floor or stand around wishing they could sit.
3. Don't push all your furniture against the walls. Create cozy moments with the middle of your room. Use a rug or table to anchor it all together.
4. Texture is key. So many people overthink color, but I think texture makes or breaks a space. Using lots of different textures creates a silent story. It creates this feeling in a room without loudly announcing the message.
5. Keep colors simple. If you want a high end luxury look, or a space that is calm and put together... stick to a palette of 3 colors. This will keep the room feeling cohesive without a lot of unnecessary noise.
6. With that being said, don't fear bright colors. Dramatic color can convey a mood very quickly even in a small space. My advice is to remain true to your 3 color palette choices.
7. Lastly pick your paint last. Paint looks completely different when all the furnishings are in place and cast colors and light reflection on the walls. Maybe the room turned out more simple than you hoped. Paint is the last ditch effort to tie it all together or push it over the edge for that dramatic feel you were going for.