The first year we made marmalade, we watched a friend make it, and then had a go ourselves. The first batch didn't set at all. So we had marmalade sauce on duck a lot that year....* But we bought a cookbook and tried again, and again. We've had consistently good luck with the recipe in the River Cottage Preserves book. Nothing fancy, or obscure, but it always turns out well. Last year we added some Poit Dhubh whisky to one batch right at the end, which seemed to give the flavour a little more depth.
This year, I decided to try the alternative 'whole fruit' method, also from the River cottage book. To the left you can see the two batches, and below, the whole fruit batch cooking.
I haven't tested either of them yet, but the whole fruit version didn't set very well, so I anticipate lots more duck a l' orange in our future, which no one will complain about.
* Put duck quarters in slow cooker. Splodge on half a jar of marmalade, a sliced orange, or some orange juice, a dash of soy sauce and cook for 4-6 hours. Voila!