Preparing a border for planting

I am currently widening a border in preparation for planting and was wondering what soil supplements I should be adding. The bed at present is a total blank canvas (old site of a greenhouse) and the soil is quite poor and dusty. I am turning it over and removing old stringy bits of root etc. Any advice on prepping this bed would be appreciated, thankyou
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10 days ago.
Friday last week after mulching with compost.
I've just rotovated it this morning
This afternoon, I'm laying another layer of compost on top, then rotovating again.