I had someone message me asking for tips with mining. My response was quite in-depth and very helpful, so I figured I'd share it here, in case it helps someone else.
"No worries.
Note that I'm using a Cobra, if you're in a smaller ship such as the Sidewinder, you'll never hit 500K an hour!
The best belts are Pristine. You can check this in the system map by clicking on any belt. It'll tell you what level of belt it is (Pristine ---> Depleted). That value is consistent through the whole system, so no need to check every belt.
Also, Metallic belts hold the best ore, such as Platinum and Gold etc., so essentially you're looking for Pristine Metallic belts in systems.
They're are 2 types of asteroid fields: Clusters and Planetary Rings. Rings are denser and ore is plentiful. Watch your ship, it can get tight out there. And stay away from the extraction sites if you want peace and quiet whilst you mine. Clusters vary in size and return, and compared to Rings, not really worth the bother.
Another good tip is to head away from the core systems to get a better chance of finding a decent Pristine Metallic belt. They are out there, but you'll want to spend time looking on the galaxy map. If you filter all the systems except Industrial and Refinery, you should narrow down some of the systems to look at.
Also spend the time checking out the System View of your target. Note where the stations are in relation to the belt. You don't want to have to travel 10,000Ls back to the station every time. Again, there are systems out there with Pristine belt rings only a stone's throw from the system's station.
When you reach the belt, be sure to park in the sunlight!! It's dodgy as hell trying to navigate a planetary ring in the dark. Turn your lights on anyway, it can help with judging distances.
I also find targeting an object, such as the nearby planet or station, helps to keep my bearings and lessen the chance of re-mining a rock.
If the rock is low quantity, move on to the next one. Don't waste time mining 2%-15% stuff unless you're specifically trying to finish a refine process. Pristine belts often have 30-50% quantities, sometimes more. It pays to keep moving.
When firing the laser, try to aim at the centre point of rotation, it lessens the randomness of the chunks flying out, and can make it easier to scoop. If it's spinning randomly, aim for the edge of the rock that's turning away from you.
Until you get good, stick with popping only 4 or 5 chunks at a time. They disappear after a short while (I think its five minutes).
If you're in a small ship with limited space, and feel confident that you can a) not crash, and b) escape any pirates; lose your shields and swap for more cargo. Do the same with the basic scanner. It's a massive risk, especially docking after a mining run, but you can greatly increase your income for the risk. It's how I went from around 250-300K a run to 500K.
You want a refinery with at least 4 bays (5 even) to make your life easier. This becomes expensive quickly, but it's worth doing and soon pays for itself.
Hope that helps."

"No worries.
Note that I'm using a Cobra, if you're in a smaller ship such as the Sidewinder, you'll never hit 500K an hour!
The best belts are Pristine. You can check this in the system map by clicking on any belt. It'll tell you what level of belt it is (Pristine ---> Depleted). That value is consistent through the whole system, so no need to check every belt.
Also, Metallic belts hold the best ore, such as Platinum and Gold etc., so essentially you're looking for Pristine Metallic belts in systems.
They're are 2 types of asteroid fields: Clusters and Planetary Rings. Rings are denser and ore is plentiful. Watch your ship, it can get tight out there. And stay away from the extraction sites if you want peace and quiet whilst you mine. Clusters vary in size and return, and compared to Rings, not really worth the bother.
Another good tip is to head away from the core systems to get a better chance of finding a decent Pristine Metallic belt. They are out there, but you'll want to spend time looking on the galaxy map. If you filter all the systems except Industrial and Refinery, you should narrow down some of the systems to look at.
Also spend the time checking out the System View of your target. Note where the stations are in relation to the belt. You don't want to have to travel 10,000Ls back to the station every time. Again, there are systems out there with Pristine belt rings only a stone's throw from the system's station.
When you reach the belt, be sure to park in the sunlight!! It's dodgy as hell trying to navigate a planetary ring in the dark. Turn your lights on anyway, it can help with judging distances.
I also find targeting an object, such as the nearby planet or station, helps to keep my bearings and lessen the chance of re-mining a rock.
If the rock is low quantity, move on to the next one. Don't waste time mining 2%-15% stuff unless you're specifically trying to finish a refine process. Pristine belts often have 30-50% quantities, sometimes more. It pays to keep moving.
When firing the laser, try to aim at the centre point of rotation, it lessens the randomness of the chunks flying out, and can make it easier to scoop. If it's spinning randomly, aim for the edge of the rock that's turning away from you.
Until you get good, stick with popping only 4 or 5 chunks at a time. They disappear after a short while (I think its five minutes).
If you're in a small ship with limited space, and feel confident that you can a) not crash, and b) escape any pirates; lose your shields and swap for more cargo. Do the same with the basic scanner. It's a massive risk, especially docking after a mining run, but you can greatly increase your income for the risk. It's how I went from around 250-300K a run to 500K.
You want a refinery with at least 4 bays (5 even) to make your life easier. This becomes expensive quickly, but it's worth doing and soon pays for itself.
Hope that helps."