Genuine stamps are 18¼ × 22¼ mm, the word BELGIQUE is closer to the top of the panel, and the letter Q has a well-defined tail.  The characteristics of the letters are slightly different in each value.  In particular, note which letters touch and which are separated.  The paper is grainy and slightly cream colored.  On the 5c & 10c the color of the cross is a dull red.
 

Forgeries