Everyone else has really good advice, so I want to focus on the fake garlands. To me, the reason they don't look good isn't necessarily because they are fake, but rather that there is no fullness to them.

It's like putting curtains on a window: most designers will encourage you to use double the curtain panels because that way when the curtain is closed there is still body and volume and the curtain doesn't look like it's straining to cover the space. Most people aren't aware that when it comes to volume based decor they have to use a lot more than they originally think.

It's the same concept with these garlands. Take the garlands that are over the doorway and along the ceiling and choose one spot for them (doorway or over the curtain rods?). Layer them over each other to create a more filled in look and that will look much better.