I usually start by air-scribing on the positive to find some pleuras. Then it's just a matter of taking rock off and exposing the exoskeleton. Once I get down to the exoskeleton I start following the pleuras. Then glueing the cross section (or positive and negative), exposing the rest of the thorax, cephalon and pygidium and then shapeing the rock. Easy. Actually, not easy at all, when you are dealing with sticky, hard matrix or spiny bugs. This one was sticky and I had to blast almost 50 hours to get this bug exposed. The matrix is harder, not as easy as Walliserops trifurcatus from Foum Zguid, which take about 15-20 hours to clean, if good preserved and you can prep fast. Anyway, as far as I know there are 4 described and named trilobites possessing a trident. This one is a new type, similar to Walliserops lindoei from Timrzit. One of the primary differences between this one and the other short-forked varieties is a more robust and different shaped trident.
Here are a few prep photos:
