So you want to make your fortune as a galactic mining magnate? Roll up to a new planet, send ships down to the surface, rip the shit out of it and bring the good stuff back. Sounds great, but it also sounds like a really inefficient way about it. Imagine how many trips from the surface to the ship would be needed to get everything? That’s a lot of fuel.
I have an alternative approach. You send one ship down to plant explosives all around the planet, hell, if your technology is up to it you can just fire on the planet from space. The goal being simply to disintegrate the entire planet. What ever you do, don’t ask how much explosive power you need – people have looked at that and you wouldn’t like the answer. In the aftermath, all of the planet’s materials will be cast into space, creating a massive accretion disk, where you can just fly around with a giant space vacuum cleaner, and pick up the bits you need. Remember, fuel is expensive, explosives are cheap. And infinitely more fun.