How to choose a professional hairdressing scissors

There are two kinds of scissor blades.
Classic bevel edge blade and Convex blade. You will choose what you are up to do with the scissors. The first one needs more energy and efforts when use while the second one is more convenient and easy to handle which is developped by Japaneses.
Be careful of the handle.
Good handles will make your wrist and shoulder comfortable and less stressful. You may choose from handles with opposite grip, handle with Offset grip and handle with crane grip.
Finally you shall choose the blade length. It is decided by the size of your hands and the techniques which you use and are command of. 
Like other stuff, you shall also pay attention to the product date,company and method.
Do not cut yourself by using scissors.