Oolite Bulletins

I haven't done it for sometime but I found Black Monks Loan and YAH worked quite well together - in the respect that you could often buy cheap at a main station and sell for lots at the Constore and then find something that was cheap at the Constore and sell it for a good profit at the main station - a few thousand credits profit - without having to leave the system and therefore jumping and thus the simple BM counter doesn't tick down by one - find a few systems that you know will have Constores and you can often make two trips in every system and make a good/reasonable profit on both before you have exhausted supplies and need to jump out again.

That way you get your well equipped ship from the loan and can trade enough stuff to pay it back in the time.

However, it must be a pain in the rear if you don't have something like YAH installed!

Add as many stations as possible to make life easy.
Hoopy Casinos -- while lacking much for sale, they offer another place to "dump" Gold/Plat/Gems for a good price.
Superhub -- While its prices are almost identical to the main station, sometimes there's a price mismatch on highly variable items, such as Furs, Alloys, or Liquors/Wines. It too is another place to "dump" Gold/Plat/Gems.
Pirate Coves! -- Excellent cheap place to buy goods, just ignore the rude welcome when you approach it.
Rock Hermits -- Not only are these sometimes added in the regular game with no OXPs installed, MORE of them get added by various OXPs... Deep Space Pirates in particular is notorious for potentially adding LOTS of them, I've had about 10 Rock Hermits in 1 system from it!
Rock Hermit Locator would really help find them, but it's so expensive. Just keep in mind that normal Rock Hermits (and even most Pirate Coves) are between the witchpoint beacon and planet OR between planet and sun.

Even the Black Monk's Monastery has its own commodities market, just like a "regular" station...so don't neglect it too!

If counting Your Ad Here Constores, you might have 6-15 stations to dock at in 1 system. Traveling between them all could take over an hour. Plan routes well, take screenshots of each menu to keep track where's the most expensive to sell to. Save game at the main station regularly while doing this -- it's more painful to lose 1000 credits early on than 10000 credits later when you have 100000+ credits to spare!