That's why it's important to get your mining skill up

Now, mine coal until you're level 60From level 1-20 you should mine copper from the south varrock mine
From level 20-40 you should mine iron from the mine near rimmington or varrock
When you reach level 40, it should be much easier to mine coal. You can mine coal at level 30, but it will take much longer, besides, if you level up with the other ores, you can either make money by selling them or you can keep them and maybe use them later I recommend this method, it's more profitable.
I also recommed that you buy and adamantite Or adamantine I always forget how you spell that or rune pick axe.
A good place for paid runescape members to mine coal, is at the mine near ardougne, which also has a bank fairly close by, this will speed up your mining and make you more efficient.
If you're a free runescape member, you can mine coal in the dwarven mines, however there isn't a bank nearby, so you wont be very efficient.