It depends if you want to craft jewelery you have to get a gold bar by buying it for 200gp or smelting it and if you want to craft hardleadtherbody or chaps and that category you have to get cowhides na go to al kharid and talk to the tanner and he will tan it for you then you need a needle and thread lots of it for tanned cowhide if your lvl 1-26 I think don't ask him to tan hard leather just make it soft leather
Start with cowhides which you can get by going to a cow field and killing some cows to make leather. Take the cow hide to Ellis the Tanner in Al-Kharid. There you can turn the hide into normal or hard leather. Hard leather is stronger but costs a little more to make. Once you turn your hide into leather, you can craft it into a useful item, like a pair of boots or a piece of armor. If you have enough thread in your inventory, click on the item you want to make to craft it.
I will only tell you 1 way. Buy shears to shear sheep then find a thing that makes the sheep wool turn to ball of wool. (you can find the thing on the middle of Lumbridge castle.