I've found a sweet spot where there are loads of courier missions and they are pretty highly paid. I'm making 40,000 - 50,000 credits every run between 2 systems in a Viper to allow me to upgrade it to a lethal killing machine. I think the missions are still good but you might have to find the right systems!
Nice.
I'd found a trading sweet spot so was hammering that in my newly purchased Cobra to get that up to spec, was buying at C200 and selling at nearly C950 with a full maxed load every time. Return leg wasn't as good but in terms of credits/hour that was my best stint since Beta 2 dropped.