Making natures is no longer "one of the best" ways of making moeny in RS. It is way to found now, with tones more rcers more runes into the game, therefor prices are dropped. I suggest finding a better way to make money if thats what your looking for, and if you want runecrafting experiance, there is much better ways then making natures.
Runecrafting isn't as good as it once was, now. You won't make too much until you are able to make deaths(65) but then the money starts getting really good around the time you can make bloods(pretty sure it's 600k+/hr, last I checked at least).
Although you lose a little money starting out(it gets to less of a loss the higher your rc lvl is, and eventually turns to profit), I would suggest you do Zmi from 44 until you can at least do deaths.