I wish I could take credit for coming up with different shaped bokeh,but I can't. Ha. A few years back a lady,who I wish I could remember,posted some tutorials of different shaped bokeh. It rocked my world. So every Christmas since then I take pictures of my tree using this technique. Seriously the most easiest thing to do in the world.
All you need to do is cut a piece of construction paper that will fit over your lens. Cut a little shaped tree,star,heart,etc.. in the middle of the paper then tape it over your lens. Thats it. Get creative,you can create all kinds of different shapes.To make it easier you can use some of those craft punches.
Tips: If you have a DSLR I find it easier with a shutter speed below 1/40. A low aperture . And you may wanna bump up your ISO.I also find it easier using manual focus.
If you have a Point and Shoot turn your flash off,set your setting to macro,make sure its dark then set an object in front of your camera,like a pencil,so its in between you and your tree. Focus on your pencil till the tree in the background blurs and take the picture. Play around and have fun=))