WIP Trading hints, tips & comments go here
Automated Station trading (via Manager)
There's an interesting thread here about how trades are currently (v3.61/v4.00b) worked out, & why your station may stop trading for a time, with Dev comments/clarifications
Personal trading via capship
I'd prefer to leve this until v4 becomes live, but ATM (other than the standard buy low, sell high - & get your trades in first) smalltalking multiple NPCs to gain stackable discounts can work effectively. if a little tedious..
Personal trading via Skunk
As above, but there may be a few traders on the station that have different prices for their wares; worth checking if you want to buy a bunch of green marines or sell off your illegal wares from a distance!
Black market trader is not available in menu "Enter-5", but still can be found in NPC list that opens in details screen and can be contacted remotely. You can sale illegal wares while out of reach of police ships.