Felting mitts

I have never felted before so I have no clue how to do it. I want to make mitts for my son. How do you know how big to make them so that they are the right size after felting? :??

well you could do these

or these

or these

I made the pair in the middle (the spinderella ones) and created an unfelted cuff to put inside so they would be closer to the wrist and not let as much cold air in. My mother stole them from me at christmas so I have no idea how well they work…lol

THANKS, I WILL GIVE IT A TRY.