In AP, you're going to wait quite some time before you can get into some real combat; a lone M4 is easy prey to enemies packing things like wasps and thunderbolts. Let's take it one step at a time and get you into a fitted ship first. Personally, I wouldn't go around picking fights in anything smaller than an M3 unless I absolutely have to.
But yes we definitely need to get you out of that TS; look for stations with money signs; they sometimes offer to sell you a ship on the cheap. You can then repair it by "E"jecting and using your repair laser. You can then use it for yourself or haul it over to a shipyard and sell it (after stripping off any useful components).
Don't bother buying a buster, for a pretty similar price you can head to Legend's Home and buy a Solano which pretty much kicks every other M4 and even some M3s to the curb.
Once you're out; use your command menu to send your TS off remotely. And while it's running, explore the surrounding sectors and make note of the stations. Make sure to actually explore said sectors so you can find those stations. When moving through sectors, make sure you check whether you're in a race's core or border sector. Core sectors are practically safe and border sectors are "mostly" safe (Unless you're in a Teladi sector where they're all too high on spaceweed or a pirate sector which is open season).
You DEFINITELY want some Navigation satellites so you can keep track of trade opportunities remotely. There should be factories in Cloud Base SW and Argon Prime, depending on how full they are you can buy them fairly cheap and sell off any extras for profitsssss. Eject them out of your cargo hold to deploy them. One at a time though. One sat per sector should be enough.
You probably realized by now that the price of goods decreases the more full a station is and increases as their stock drops. So buy low, sell high. "Race" trading stations are the exception; their prices never change and is always at average value.
Some early trading spots:
I personally never bother with Energy cells unless it's for starting capital, but Power Circle has several SPPs and several nearby Ore mines; easy. The Boron areas at the upper-left part of Argon space are almost always starved of ECs due to having all of their Solar Power Plants 3 sectors to the east in Queen's Space.
If you've got the capital, trade Ore. It's cheap, legal, and loads of stations need it. Ore Belt, Power Circle, Herron's Nebula have several mines that you can snag a cheap deal from. The biggest payouts are found in manufacturing stations, particularly weapons factories and such. Cloud Base SE, Red Light, and Argon Prime usually have those stations. The Boron in the NW areas have subjected themselves to resource placement stupidity and also need ore.
Meatsteak Cahoonas are eh... They sell quite well in Argon Space but you'll find limited markets elsewhere. I would generally stick to ore unless all those stations start to get full; that's when you feed them cahoonas so they can start using up ore. Most Cahoona Bakeries are in Cloud Base SW and Home of Light, tech factories are the highest buyers here.
I wouldn't bother with Cloth Rimes, too few stations deal with them.
Finally, there's Delaxian wheat and Space Fuel Distilleries. Cahoona and Rimes Factories buy wheat, but the best place to sell them would be the Distilleries; you'll find them in Herron's Nebula. One thing to note is that Space Fuel is Illegal so if you get caught that's all of your profitssss and a fair chunk of reputation. If you do want to smuggle, Trading stations and Pirate stations are your only buyers. Trading stations should be easy to find, but Pirate stations respawn elsewhere when found and destroyed by AI, so I can't really help you there.
Once you've got a decent nest egg we can talk about moving up to combat.
There are also opportunities in Teladi space, but pirates...
The Paranid can build ships but they sure can't plan an economy; their "Priest Circle" sectors are easy money if you've got the transport capability. The problem is that you'll have to run through a few pirate sectors; and that's not exactly feasible in an unarmed, unshielded Mercury.
Split economy is mostly self-supporting from what I've seen. And Boron sectors that aren't linked to the Argon are generally poor.