Basically, fly off in any direction for >150LY, then sell.
Ideally, you would have two "zones" where you can collect (multiple) rare commodities on various stations until your cargo hold is full. Then travel to the other zone, sell everything and start filling up again.
I always choose the "fastest" route so I have less jumps. Then I let the computer plot the course or have a coffee break while refueling every now and then in a corona.
After delivery, when your hold is (almost) empty, it's also a good opportunity to do some bounty hunting and camp a nav point for a few minutes. Just to keep things interesting.
Further, get the scan package, so on the way, you can chart star systems. Analyze the star for fast cash or fly and analyze everything in unexplored star systems for a little detour and even more cash.
Also, while docking at various systems you can check the upgrades for sale and spend your money. Or take local delivery jobs if it's on the way and you have cargo space available.
Makes an interesting gameplay without just hauling freight from A to B on the same route over and over again.