Molex makes a hand tool that works quite well for crimping their pins. $34 at Mouser:
You will also need an insertion tool appropriate for the housing that you are using. It works wonders stuffing your pins into your housing. I use this for SL connectors; don't know what is recommended for KK:
(the Mouser picture for the latter is incorrect)
And of course use stranded wire as has been already mentioned...