I also found that finding a good trading route yourself takes a while. You may luck on to something really good or settle for a mediocre run. And then because of the capacity of the big ships, find you alter the prices and after a few days have to move on. I got fed up doing my own finding and did the equivalent of talking to people - listening to them. Or to put it another way putting the search words 'trade' and 'trading' into this forum, and thereby getting some ideas which proved quite lucrative. If new to trading here's an initial run for you.
https://forums.frontier.co.uk/showthread.php?t=151793&highlight=100
https://forums.frontier.co.uk/showthread.php?t=151793&highlight=100