As promised, here are the blade settings I have found work well with my Silhouette Portrait machine.
I'll add more as I use different types of medium.
12x12" Patterned Paper (Like the ones we get from Papermania - usually about 160gsm)
Speed: 5
Thickness: 30
Blade: 2
Valley Craft White Card (200gsm)
Speed: 5
Thickness: 33
Blade: 3
Valley Craft Pick 'n' Mix Colour Card (225gsm)
Speed: 5
Thickness: 33
Blade: 4
*Double Cut On*
Bersan Double-sided Pearlescent Card (250gsm)
Speed: 5
Thickness: 33
Blade: 4
Silver Mist Iridescent Paper (120gsm)
Speed: 10
Thickness: 25
Blade: 1
12x12" Glitter Card
Speed: 3
Thickness: 33
Blade: 6
*Double Cut On*