Level 1-6:
If you plan on training mining only, then you can do the rune mysteries quest and mine rune essence to sell for 35 each. If you plan on training mining and smithing, then mine copper and tin (Falador mine is best due to the proximity of the bank and the furnace) to make into bronze bars that can be sold for 100 each. Check the forums on Runescape to find bronze bar buyers (you don't have to be a member).
Level 6-21:
Either way, by this time you should have enough money to buy a steel pickaxe from Nurmof (inside the Falador mine). Use the steel pickaxe and continue mining the essence or copper and tin.
Level 21-31:
Now, go buy a mithril pickaxe from Nurmof with the money you've earned and use it to mine iron rocks in the southern portion of the Falador mine (low level miners mine here). Sell the iron ore at Falador bank for 100 each on world 1-5 (whichever isn't full when you look).
Level 31-41:
Go buy an adamant pickaxe from Nurmof with your money. Mine the iron in the northern portion of Falador mine now. If the scorpions hurt you too much, then you can still mine the iron where you were before.
Level 41-60:
Go buy a rune pickaxe from Nurmof or from players for 32k (32,000 coins) if there isn't one at his shop. Mine any coal rocks you can find (many coal rocks will be used by higher-level miners). Sell the coal for 180 each on worlds 1-5. An alternative may be to mine gold rocks in the crafting guild if you have over level 40 crafting or anywhere else you can find them. You can then sell the gold ores for 450-500 each (just find a buyer in the forums).
Level 60-70:
You now have access to the mining guild. There are 37 coal rocks and 5 mithril rocks in the mine. You can continue to mine coal or gold, but you can also mine mithril rocks that sell for 400 each on the forums.
Level 70-85:
You can continue mining the rocks you did from level 60-70; however, at level 70 you can mine adamantite ores that sell for over 1k each.
Level 85+:
Congratulations, you can mine rune; however, for f2p (free to play) players, the only rune rocks are found in high wilderness. The ores can be sold for 12k each, so it's your choice to mine them or not.
