First vou need to find a profitable route. Why not became rich in the process?!. Use a short one and with a loop. Buy at A, sell at B, buy at B, sell at A. A good source to this is EDDB site.
Pay attention to the landing pad size and any restricted product. You don't want to find that you will not be able to dock your anaconda full of precious cargo or that you are hauling illegal products for that system.
Make sure all the possible optional internal modules are cargo rack. I don't use shields generator, for example.
I did this with a type 6 with 100 tons cargo bay.
Leave a comment about this, I wanna see what you guys think about this. o> commanders.