Well, you said it yourself. You need work, marketresearch to find out what is proftable. (like production,invention, trading,...)

But what helped me is:

Take the list of the PI-materials (skip raw) check buying prices with eve-central or directly market export in the trading hubs. check traded volume.

once you found a material the real work starts. check possible planets, production lines, transportroutes.

one/two tipps: there are good excellsheets, never export rawmaterials from planet (process at least to Material-Lvl 1), keep the links as short as possible, sometimes it´s better to have two planets extracting only one material, check if buying T1-T2 on market and processing to higher in higsec near trading hub ist better than doing the long way; if you have to transport materials to sell, keep in mind that the materiallevels have different volumes. calculate that with your cargoamount ,.........

hope it helps ;-)