A warm color on the wall is important. Paint is easy and fairly inexpensive.

A down comforter is one of the most inviting things you can add to a bedroom. I like to fold a down comforter at the end of the bed so it is plump in the middle. It adds a warm and cozy look.

Lots and lots of decorative pillows piled on the bed will give in a warm and inviting feel. I like to prop four sleeping pillows upright to serve as the backdrop for all the decorative pillows.

Accessories in general add warmth to a room, but you can switch out your accessories to showcase only ones that reinforce the cozy atmosphere you are creating.