Buy sapphires,gold bars, and balls of wool in the ge. Go to Port Phasmatys or Edgeville and make sapphire ammys, they give 65 xp and are cheep. After you string them all, high alch them (450gp each) or try and trade them for another item. Keep doing it and you will get crafting lvls quick
if you have alot of money (mills) you can make ruby or diamond things too.