You need to be at least level 48 Smithing to be a good Smither. You can buy your own ores if you have the money, or you could mine the ores yourself. Unless you have a Ring of Forging, don't smith iron!

>From level 1-15, smith 131 Bronze bars.
>From level 15-30, smith either 592 Bronze bars or 293 Iron bars.
>From level 30-48, smith 1,858 Iron bars or 1,267 Steel bars.

Now that you've got ten to level 48 Smithing, you can incorporate this method of earning money with method 2 - High Alchemy.

Earning Money From Steel

Get 2,000 Coal and 1,000 Iron.
Smelt them into Steel, and then Smith them into Steel Platemail.
Use your High Alchemy spell on the plates for 1,200gp each, or sell to Horvik in Varrock for no less than 980gp.
You can make anywhere from 196,000-240,000gp this way!
Mithril at Level 68

Get 4,000 Coal and 1,000 Mithril.
Smelt the ores into bars, and then smith them into Mithril Platemail.
Use your High Alchemy spell on the plates to make 3,112gp each.
After High-Alching the plates, you've made 622,400gp!
Steel appears to be better since you can make more money with fewer coal, and iron is much easier to get than Mithril. At level 99, go for the big kill...