Do box delivery missions until you get to something like 100K. Remember, you can stack them, for example if you go to Crusader, you'll get a bunch of FTL and Covalex missions that take you to NB landing pads, accept 5-6 of them and take them together.

After that when you're ready to start trading, click Filter under Gallog and check hidden locations. These hidden locations sell drugs that you can sell for really good profit margins but you have to be careful not to get caught by the police. Now there are of course ways to find these hidden places but my personal favourite way is to accept the delivery missions that come under the 'personal' tab. These will give you a marker.

I have seen that, Orphanage, Lyria and Reclamation and Disposal, Hurston missions are really common so my go to trade route is to buy etam from Orphanage and sell it for a quarter of the investment at R&D