The world is your lobster with turning..... Wood is good
But if you think plastic is fantastic then it can be a bit baffling....
Most things can be turned but your right they can be very different, always sharp tools, small cuts and good speeds will see you right...
Acrylic can be brittle it depends on the amount of hardener or type used...... Acrylic Inlace is a real splinter one to watch... If your using sharp tools, you should also be producing long white ribbons which go everywhere and wrap around everything 
Casein, ebonite and omas again nice and easy to turn but can be smelly as can horn and antler.....
My recommendation would be to try reputable blanks ie GPS or Kirinite or Axminster/ Turners Warehouse blanks, till your comfortable then you should have an idea where and what to buy from the pleather of home casters especially hybrid or watch part blanks.......
