I don't know how it worked for others, but I got rid of the discover scanner in favour of more cargo. Kept the shields, upgraded them when I could until I could afford the hauler or an Adder. Interdictions happen all the time, so I tended to go multipurpose: Sidey-Adder-Cobra, and upgraded them to A fits as I went along... usually goes power plant-shields-power dist-FSD- guns.
I keep enough back to pay to rebuy my ship (twice) if lost to interdiction, and until I got a 10 milion reserve, I took a ton of hauling missions, as that cost me nothing to haul in terms of my ingame cash layout.
It's worthwhile to get ar least 5-10 jumps out from the starter system, and then try to find a decent trading route bewteen 3-4 systems that makes it worthwhile to haul between them. I have tons of notes from the routes I've created. As ships get larger, landing options get fewer, but you should be okay for a while.
Buy cheap, sell dear, and close. 1000/ton is okay profit, IMO. Fly safe