In addition to the above, I highly recommend you do you a little Dungeoneering and obtain the scroll of cleansing, it's only 20k tokens but can save you a bit when training Herblore. It gives you a 1/8 chance of making a potion twice as fast but, more importantly, a 1/10 chance at saving a second each time you make a potion. If you want to save a bit more at the expense of it being a bit slower, it can also save you an herb when making an unf pots IIRC.