When I first started OSRS I wanted to get my cash stack up to at least 100k. So I skilled a little bit and got about 10k, with that 10k I tried so many low gp items but it wasn't making any money. So I saw ashes on the floor and out of boredom I picked it up and sold it on the GE and I thought it would sell for maybe 5gp since they're all over the floor. But it was selling for 40gp each at the time. So I decided to try to flip those and pick some up while waiting (1.1k an inventory was great at the time). I eventually found a pattern in the ashes' prices, they always peaked at 50gp and fell down to 20gp. This pattern happened over a course of a week. Once I found that out I started buying thousands of ashes when it fell and sold it when it was peaking. That's when I started to pretty much double my money every week. I haven't done this method in a while and not sure if it still works.