Two things:
Firstly, you can land a few km away from the base and just cruise around. Before long, you'll find "wanted" skimmers guarding a stash. You can find about 12 per hour doing that. It's best to drive in a general direction rather than cruising randomly because you might end up back at the same stash with no skimmers.
Secondly, if you can find the base's generator, you can fly in and blast it before you take much damage from the turrets. Killing the generator stops all the base ground defences. At first, you can fly in and have about 10 seconds before the trespass timer goes off, but after several visits, they open fire as you approach, so you have to go straight for the generator. You need a ship with good shields to use this method. Also, there will be patrolling ships guarding the base. They don't bother you until the trsepass timer goes off or you open fire, so, with good shields, you can tank them while you do your business. To summarise, you fly in, blast the generator, blast the skimmers, turn around and boost out of there, which takes about 30 seconds for your 12 skimmers/stingers. You only use dumfire missiles to blast the generator and skimmers.
Method 1 gets you 70 million an hour when allied. Method 2 gets you an average of 170 milion an hour. That's assuming that there's plenty of skimmer missions being offered at the station. Method 2 puts an increasing bounty on you. I went up to about 500k bounty after taking about 5 billion for kiling the skimmers, which meant that I kept getting interdicted by bounty hunters for a week afterwards, which slows you down in whatever you're doing.
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