Just like Vavrik described, I also do runs with multiple hops only to take a stroll through the system and have a reason to do it. I basically open up a trading sheet I found online, see who sells what and who buys what and set my next destination. I do that with small cargo ships, usually a Freelancer. Not a lot of profit, but it doesn't matter.
For an actual profit, I use larger ships and only on short runs, because the cargo costs a lot and a crash or a bug may leave me a poor man. So I do either Astatine from Ita to Loreville with a Cat (about 100k profit), or Laranite from Arial to Lorville with a Constellation (around 50k profit). No point takin' a Cat for Laranite because the shop is always short on product to sell (also it would take about 1.5M to fill one up).
There are other profitable products out there, but I found that they always sell in short batches, which basically affects your profit by heavily enlarging your time for the whole operation. That's why I quit also running drugs, the problem with them being at the other end: the console only buys them in small batches (15min to bring them in, 3h to get rid of them).