You gain skillpoints as you use the exact skill, the lower your skill the easier it is to gain, apart from when the skill is like 10 or less because it fails alot and thus less gains. Certain things are difficulty based too, I'm pretty sure crafting would act the same way, i.e you have to craft more difficult things as your skill gets higher to continue getting reliable gains. Also once a skill reaches 60, it activates a ' skill fatigue' system, which basically allows you to only gain so much in a skill each day, it tells you when the skill is exhausted.
You might find stuff on the forum that people have written about their own experiences so far with the crafting skills. To mine ore you are better off going to Minoc as there is a big mine there right next to the city, there isn't any mining caves near Britain. It's probably the most newb friendly mining area anyway, not sure what king has taken over minoc and what he has set the laws on but I assume it would be safe.