Ferret kits biteing

Hi I have recently became the owner of 2 ferret kits I have had them for 2 weeks now and they are 12 weeks old, how do I make them stop biting me! 
I have tried scruffing and hissing at them but it seams to make them more aggressive?
What am I doing wrong?

Thankyou for your replays in advance
Craig 

1.  Scruff them by the neck, gently drag them short distance on the floor...hiss at them.

2.  You can put some bitter apple on you....makes you taste nasty.

3.  Time outs - put them in a travel carrier for 10 minutes.  (not their cage)

4.  Try to distract them with a toy....when you know they are coming to nip you.

I hope this helps