With nothing I would go to seers village and pick flax. Getting 200k-300k should not take too long. Once you have that much buy some decent gear and go kill green dragons. Or if you want kill druids in either edgeville dungeon, ardougne, or yanille (depending on your theiving level). They will each weild about 300k-500k an hour depending on your stats.
Once you reach somewhere around 5m or so you can start merchanting on a low scale. Your returns will not be anything amazing with such a low amount but it is a good start.