Throw it all in! Seriously. Add everything in except the flour.
Cook on high for 4 hours or low for 6-8 hours.
30-45 minutes before your filling is cooked add the flour, mixed with a little water to make a paste, as this will thicken your sauce.
Once your filling is ready you can either top with mash, and cook on high for 1.5 hours, or you can move to the oven for 30 minutes.
I like to scrape the top of my mash with a fork, to get crispy edges, and cook for 30 minutes at Gas mark 6 (200C).