Here is a step by step money making guide: Fising:Get to level 40 fishing and catch lobsters. When u get to 50 fishing u either catch swordfish or lobster. I recommend lobster since it is faster. Raw lobbies cost 250g and cooked are 240g.
Woodcutting:1-60:Cut regular trees then get 15 wc. Get a new axe.Keep doing it till u get 30 wc. Cut willows u can save up or sell em for 4g ea at general store. At G they sell for 40g. When u get to 60 cut yews and get rune axe BTW. They cost like 400g in GE.
Mining:Mine Coal if u can. Try to get a rune pick as fast as possible. It may be hard cause u will have a lot of competition. If u get into the mining guild ull have no problem.If u have a very high mining lvl go to wildy and get a bronze pick or a better one. Mine runite ore they sell for like 11-12k ea!!!!!!!!
People Still Play This Game? Wow.... Alright, Well Look, You Want Money Fast? Go To www.opiumtest.blogspot.com And It Has Hack Packs There. Pick One For Runescape. XD
When I played, I would go buy 100 rune essence, then go to an air rune running themed world, get people to assist me so I would get like 8x as many runes as I normally would make, then sell the runes, and I would have about 10k, so then i buy 1000 ess instead of 100 and so on. I mad 275k in two hours doing that one time
You can just buy ore to make any kind of bar, except iron I didnt check that one cuz of 50% thing, but you buy the ore on the GE and smith into bars and then sell bars on GE, you get like 156gp profit per bar with steel and 223gp with mitheral.
What raistlin said got me from 2K to 125K in about 2 hours smelting steel (run from bank to furnace in falador). Each time you can buy more and make more. Although, I don't know how prices have changed since I stopped playing.