Most people, when asked how to iron fleece, will tell you it's not possible. They will tell you that the fibers will be melted by the heat of the iron. But as long as you take the proper precautions, you should be able to get rid of the wrinkles in your fleece.
Step 1 - Dampen the Fabric
The best way to iron anything delicate is to have it damp. A good way to do this is to wash the fleece material. Remove it from the dryer before it's dry, but after it has had the chance to warm up. The warm, wet fibers will be loose and ready for ironing.
Step 2 - Set Iron Temperature Low
Preheat the iron to a low setting for fleece, as well as polyester or rayon. These are other plastic based materials. By using the lowest setting for the iron, you will have a better chance of not causing any harm to the fleece garment.
Step 3 - Cover and Iron
Cover the garment with a thin cotton sheet or clean rag before ironing. This will help to protect the garment from being affected from the direct heat of the iron. This works on fleece as well as fleece-lined materials. Make sure to hang the garment up as soon as you're done.