I use the Decal paper
I use the Decal paper extensively and they are fairly simple. You should not get a blob. First, The paper is only good for laser printers. Make sure you use that.
Second be sure to remove the protective film form the decal paper before printing on it.then when it is made, but out your decal and soak it for 45seconds to 1 min and then slide it on to the glass.
Make sure you are doing the above and give it another try.