This is a good starting way of making money before you move onto the big stuff, Smuggling / Raiding is an easy way of making money and it's well worth your time. It's rather easy once you get it going and it is still possible to do at an early game stage. It can get you about a billion credits in about a few minutes.
1st/ Find an enemy faction with a sector mainly full of mines. If they have any other type of stations cargo ships will bring unwanted cargo.
2nd/ Scan cargo ships (by selecting them and getting 1 kilometre away from them) and see if they have anything in their cargo hold, when you select them if they have anything you should see a name pop up at the bottom of their " icon " at the bottom right of your screen. Then destroy their engines so they can't escape, destroy them and take the loot, make sure your cargo hold is set to pickup stolen cargo.
3rd/ Go to a smugglers hideout ( Hidden mass Sectors sometimes have them ) And sell your stolen cargo untill you have atleast 4 million ( unless you already had 4 million )
4th/Go to a friendly faction with at least some mines in their systems and buy a license from them ( the 2 million credits license ) as you want to transport dangerous cargo in their systems + so if you forgot to get rid of stolen cargo or other you don't get fined.
5th/ Steal loot again { Repeat of 2nd step }
6th/ this time unbrand your loot ( Only do Antigrav units, Fusion Generators or Mining robots as they matter most, some are still worth it but depends on your cargo-space ) and sell stolen loot that isn't the good loot.
7th/ Find mines in a friendly faction that you got a license from and sell your loot to the station that sells for most ( trading systems help a lot ) and then rinse and repeat.
Now after you've earned your first couple billion credits start searching for turret factories, keep your eye on Tesla Turrets as they are one of the most high tech weapons in the game and can go up to 240,000 dps ( usually the cost gets to high to sell well )
Around about 150,000 dps you can have a cost of 20 million credits per turret but sell for 170 - 190 million credits.
But you have to keep sure the weapons have no Targeting systems in them, Are Exceptional Level Turrets and have max components in them( excluding Targeting systems ).
Also those turrets I mentioned were only so high because they were ofc close to the very core, besides.. around the barrier you will still earn a butt-load of money anyway.
So look out for turret factories with teslas in them and start to collect these ingredients:
Industrial Tesla Coil
Energy Cell
Conductor
Copper
Energy Inverter
Electromagnetic Charge
Also if you want to quickly build lots of turrets just go to the amount bar at the bottom left when creating a turret and also when selling your turrets make all the new turrets labeled as trash ( if you hover over them in your inventoy a little trash icon shows up just click it... ) and head to an equipment dock.
Then just click sell trash in the Sell Menu, there's no loss of money when labeling a turret as trash as I first suspected.
If you want to make the big big money, just make your own factories for the components. If you add enough assemblies and cargo you can get to a cargo space of 25,000 for each item ( depending on its volume ) and assemblies will just improve the overall speed ( But also those are limited in how much they can inprove the speed ( Untested but I remember it was somewhat around 25% increased Speed) ). When you have enough money I heavily recommend upgrading your stations for more parellel production which is literally just doubling your overall speed of production (You'll be able to see the production lines under the station when you interact with it and under the Hull and Shield ).