Looks like the Big Money™ are in rare goods. Each rare good is only sold in one station and becomes worth more the further away you go before selling it. The prices on thhis graph are a bit out of date, but the curve is pretty much the same.
So the trick is to find several systems with a rare good, 100+ light years apart and do a circuit of them that takes long enough for the first station to replenish its stock.
I tested it today.
Cobra. 34T cargo capacity.
15LY jump range. (More than 15ly actually, but 15ly was the longest jump I made).
Eranin (Azeban City): Fill cargo hold with Eranin Whisky (rare good). About 60k cr for a full cargo hold.
Jump list:
Eranin -> BD +47 2112 -> DG Canum Venadcorum -> Wolf 424 -> DEN 1048-3956 -> LTT 3572 -> L 32-8 -> LHS 160 -> L 17-428 -> Chi Eridani
Chi Eridani (Steve Masters Station): Refuel (~6800 cr). sell Eranin whisky for ~320k cr (260k cr profit). Fill cargo hold with Chi Eridani Marine Paste. go back to Eranin.
Depending on interdictions, time spent in stations and how long you take to jump, a full circuit takes 30-45 minutes and netted me about half a million credits.
They're probably going to tweak the prices or commodity availability before release, since th emoney are ridiculously good atm. That said, once you get a hauler or cobra with a rating C, B or A FSD, hauling rare goods in a multi-station circuit is probably going to be pretty profitable.
That is one sexy beast... Here's hoping they release some more flyable Empire ships in the future.
There's 2 at the moment: Imperial Clipper (Light warship) and Orca (Passenger liner/cargo hauler).
Other imperial ships devs said would be flyable in the future: Dolphin (Orca's little brother), Imperial Courier (Scout), Imperial hunter (Short-range fighter).
I wouldn't mind one of these in lieu of a sidewinder: