So; some (very basic) learning which hopefully may help others:
After arriving in a system and 'honking' (using ADS), dont rely on the system map to show you the planets; you need to use the FSS to fully scan the system. A 'honk' will tell you how many bodies there are in a system but, unless you have been to the system before, these wont show up on the system map until they have been scanned with the FSS. I'm still not clear what the earliest point in this process is that you can tell whether it is a virgin system.
When turning in to Universal Cartographics you are paid by the page so dont be disheartened when you only see a couple of million at the top of the page; after a decent exploration run, the credits will flow in for several pages more.
When using the Galactic Map, in the View tab, using 'Map' you can filter all sorts of things than first appears from the drop-down menu. Scroll the list and there's 'star class', 'visited stars' and all sorts of goodness. Trying to then spot some of the rarer things, such as 'tech broker' is another skill...