If you're a free player, here's an overview of the options that are available to you. The best choice is to purchase a the green dragonhide bodies. You can purchase the nats or bodies through the grand trade. The amount you earn is 20 gp per alch. The maximum you can lose is 100 grams. It will take around 200 hours to finish 55-99 high alching, which costs between +3.9m between +3.9m and -19.8m. There would be an alch of 198k.
However, 55 magic would be the best first step. I suggest investing between 200-300k and $300k on fire strike or earth and then using the remaining funds on lessers. To achieve this, you could use firebolt or fire strike on monsters. I don't know what it would cost or be due to monster drops being random, and all.
You could also use curse to increase your level. You would need to buy 99 of these items which would total 17.9. For this to happen, you would need to purchase 449k body parts, and 898k water supply (don't make use of the earths, you only need 3 instead 2 waters so it will be cheaper). You should wear armor made of heavy metal and anything else that provides the negative (+) magical bonus. Your curse isn't going to be a threat to monsters, so you can repeat the spell on him. For failing, you still get the same exp
With the increase in the price of Essance pure at Grand Exchange (and the time i became a Member at the same), i've been able to make 300k+ per day in less than 3-4 hours. Pure Essance costs 115 dollars +!!) but at my level, there's not much i know of that cosrt heaps, i already have full rune and a full mystic (red/black style) obsidian cape! Granite maul. I want to purchase something cool that isn't just rune (g/t) (i will get some (g/t) things), or mabey ill give it to someone else. If you want to know more about can go rsgoldfast