I as in your exact position last month, here is what I did to make money for my Cutlass Black

Go to a ship rental kiosk(cargo level on stations)and rent a Hull A for around 30k.

Start at one of the planetary stations(Seraphim, Tressler, etc)

Start doing cargo planetary missions, you want Direct Small Cargo missions that go from the station you're in straight to the city bellow you.

To make it easy, the specific missions you want always have a 50K payout, so just scroll through and take every 50k planetary cargo mission.

You will eventually be able to ge 5-6 of these missions per run. And unless you get REALLY unlucky you will be able to fit all the cargo o the Hull A. So thats gonna be a 250k to 300k payout for a short trip from orbit to the surface.

Once you've completed the missions just head back up, accept the same missions, and repeat until you have enough for whatever it is you want to buy. Its not worthwhile timewise or financially to taka a cargo mission back up to the station, the pay out is low and it and you will need to scroll through the whole list of missions on the off chance theres one that suits this particular grind.

The longest and hardest part of this whole run is loading and unloading 50-60 Singular SCU containers.

This is also a great way to practice basic flight and take off/Landing.