I think pillows make the biggest difference in a room. If you instantly want to make your home look more expensive and interior designer-ish, get yourself some choppable pillows.
I know some people hate the look of chopped pillows but go on Pinterest and find expensive looking rooms. I will almost bet you money that the space has chopped pillows of some sort.
Okay - now look at one more thing regarding pillows in those expensive rooms. You see how they are really full? They look really nice and plush.
Usually getting pillow inserts like this are super expensive. I used to go to the back of HomeGoods, find as many clearance pillows that pass the chop test, and buy them specifically for the inserts. There was a lot of effort put into it. hah!
BUT, I recently discovered these pillow inserts from Amazon. They are SO, so, so good. I will never go to another pillow insert. They're affordable, extremely fluffy, and create the perfect chop. They also have basically any size you would ever need.
TIP - Always buy a size up than your pillow cover. Example, if you buy a 24x24 pillow cover, get a 26x26 pillow insert. It will give you the perfect fullness.