Okay, state blue is a dark colour, with a fair amount of flake in the sun. If you're working by hand (i assume you are?) this is what i think you should use for good results:

Wash with a lambwool washmitt, dry with a waffle weave towel. Clay the whole car to remove surface contaminants. Then polish with either Clearkote Vanilla Moose Glaze (not a glaze it's a polish!) if you want some cut, or Autoglym Supreme or Ultra Deep Shine, as these are suited to dark colours, and will help to mask swirls and scratches.

If you want to richen the shine, you should now apply a glaze - Clearkote red moose machine glaze is best.

Now seal the finish; Autoglym Extra Gloss Protection for a nice, durable finish, or Poorboy's EX-P to really make the flake pop in the sun.

Finish off with a good quality finishing wax. For your colour car, i'd use Poorboy's Natty's Blue.

Then stand back and admire the shine!

Gareth