I have never tried anything besides basic (non-rare) trading, so I cannot speak about anything else. But with the recent trading/economy changes... First, it royally screwed up my trading routine. At that point, I was using a T6 and making around 700 per cargo space on average, with each trip taking around 6 minutes... Not great, but not aweful either. Once the patch happened, it became very difficult to make consistent profits that way because I was trading at some small docks, and the supplies were low enough that the prices would collapse after only a few runs.
Unfortunately, the changes have completely screwed up the prices on Slopey's BPC tool, so using that was not going to help. I had to manually fly around for a couple hours to scout out new trade locations... Until Slopey's tool has had a few days to be fully updated, I am not sure if there is a better option. Ultimately, I now have my T7 and am making 1,000 to 1,100 per cargo slot, and each trip takes roughly 6 minutes. That breaks down to a bit over 2 mil per hour. If you can do better, then obviously ignore what I have to say. But if you are struggling, then perhaps I can help. While there may be no way around manually flying around to ports to see what goods they have (and keeping track of the prices), there are certain things to look out for...
1) The basic math to making money... High profits per trip (obviously)... and quick trips. Making 4-5 jumps per trip is ok, but making 1-2 is much better. Each additional jump is not a huge deal, however to make money, you will have to be very repetitive. So adding 1-2 minutes with extra jumps per trip... adds up when you repeat the process over and over again. But what is far more important is the distance to the stations. 1000 Ls is fine... Less is better... But 10,000 or more will really slow you down. So when you start searching, if you jump into a potential system and find that the stations are too far away, don't even bother with them. Just move on to the next system and look for closer stations.
2) Making 1,000 profit per trip eliminates many goods from the equation. Food cartridges just aren't going to do the job. Right now I am using Resonating Separators (6,000-ish) and Tantalum (4,000-ish). Realistically, 4,000 is about as low as you can go to make 1,000 profit. Palladium and Gold are more obvious choices... but there were two major issues I ran into. I was only able to find those two goods at small outposts. Small outposts have small supplies and demands. So they may have the goods you are after, however once you begin your runs, the prices at those places start to collapse and you will be forced to find a new trade route. And now that I have a T7... small outposts are not even an option. But in general, a large population station will have much greater supply/demand for goods, and will not experience price changes when you start your runs. So use the navigation tools and eliminate the small population outposts from the map; They are not worth your time.
3) You can also remove agricultural and terraform systems from the equation. While it's possible to find a diamond in the rough with these places, there is vastly greater likelihood of finding a good pair of trade stations with high tech and refining. Unfortunately, while extraction is good too, I have not found any places that are both high population and export extraction goods... Let me clarify. They may export them, but they are not listed as an extraction exporter (hence the need to manually fly around to each station to see what they have).
4) There are many potential goods that can make you 1,000+ Credits, but the hard part is finding two stations that each have a set of supply/demand which compliment each other. Getting 1,000 in both directions is the goal. The most common goods to be able to pair together are (1) any metal that is 4,000+ credits, (2) Resonating Separators (these are a gold mine, but took forever for me to find a supplier), (3) Superconductors, (4) Consumer Technology, Performance Enhancers, and Progenitor Cells. Unfortunately, it's difficult to know which of these things any given station may have before you visit. But the best bet is by starting with places that show their exports as any of the high-priced metals, or high tech. High tech will usually have a demand for metals, so once you find one, all that is left is finding a metal-exporter to pair with it. Palladium seems like the ideal choice, however I never found a good supplier. Gold ended up being much more available in large quantities, so I would recommend that as your target good when scouting for metal exports.
5) At the end of the day... even once you find two great stations... This approach is going to be a massive grind... Short trips... Quick turnarounds... over and over and over and over and over and over... But if you have the time and patience, you can make a pretty penny this way with no real risk or fluctuation in profit.
