Use the telecenetic grab and take the whine of zamorak from the captured church/temple near falador.
It's about 800K / hour and works for f2p. The only problem is other people doing so you have to find a good server without someone doing it already
Depends if you are on 07 or eoc, if its 07 my personal preference is fletching, it is slow at first buy once you can fletch yew long bows you will roll in the profit I made about 8M in about 12 hours of fletching