The perfect time to practice casting is when there are no fish annoying you. If you play golf it is no good practicing during a round. That's not how the pros do it. Over winter you can set up a rod up and practice without any annoying fish - in the back yard is okay, but a nearby park is good and you can amuse the locals. Casting in the park is fun and attracts the locals - as does a gorgeous dog - everyone makes comment or comes for a chat. It is great.

Seriously though, practice casting is both therapeutic and rewarding - and purposeful practice where you give yourself some tasks is even better. 

I urge you to go to the leading fly casting site in the world: https://www.flyfishersinternational.org/

You will need to put your email address in, but that is all. You will find a huge resource that will help you be a better caster. Being a good caster is way more important than fly choice as it is only when you can get your fly in front of the fish that it can eat it. I would take presentation over imitation any time.

We have put together two options with bright orange lines. Line with heavy butt 2X leader and indicator wool - or complete with reel. These lines are in a colour that is easiest to see - and are double taper. This allows you to see and feel what is happening. The double taper allows you to carry line in the air and see what happens when you change your casting stroke. This line is recommended by one of Australia's most highly regarded casting instructors, Peter Hayes. The line suits both 5wt and 6wt. Line $50. Line and reel $140.     

You can find the line - or line including reel here. Shipping is FREE

Other resources:

Book a learn to fly fish course here (if in Tas.) 

Private lessons with Peter Hayes are here: https://www.peterhayesflyfishing.com/