Levels 1-15 - Bronze Bars
You will be making bronze bars which require 1 tin and 1 copper ore then you'll turn the bars into the highest level bronze item you can.
Levels 15-30 - Iron Bars
You will be doing the same thing just with iron bars. Just like in real rs you can fail to smelt it.
Get around that by either making or having someone make you a ring of forging.
It is the enchanted ruby ring and it cost 5 fire runes and 1 cosmic rune along with level 49 magic! They do break so maybe make a few for the harder modes.
This will stop you from failing to smelt an iron bar so for sure worth it!
Levels 30-50 - Steel Bars
You will be doing the same process just with steal. You no longer need the ring of forging but each steel bar uses 2 coal and 1 iron.
Your inventory should look like this each run for max amount of bars. 9 iron ores and 18 coal you'll be able to make 9 bars an inventory.
Levels 50-70 - Mithril Bars
You will be repeating the process just with mithril. You inventory should look like this.
5 mithril ores and 20 coal which will allow you to make 5 bars.
Levels 70-85 - Adamant Bars
You will be repeating just with adamant. Inventory should look like this.
4 adamant ores and 24 coal which will make 4 bars.
Levels 85-89/99/120 - Runite Bars (fast xp but click intensive)
Here you will start using rune which will be click intensive.
Now stay with me here while I explain this setup. It takes 8 coal and 1 rune ore to make 1 bar so at most you'll be able to make 3 bars
if you were to do a normal setup but that will require more clicking. Put 10 rune ores in your inventory and fill the rest with coal.
You'll be making 2 bars each run but when you go to bank instead of grabbing rune and coal you now only need to grab coal.
Level 89-99/120 - Corrupted Bars (Requires Access to Prifddinas)
You just need the ore of this same type and not any other, theres a furnace and a anvil right next where you mine it.