Welcome to Leaf's Money Making Guide!
This is my money-making guide, BASED ON personal experiences.
Combat
[Level 10-40]
Probably the most basic, but very profitable. There are two things you can do. First is at Lumbridge Farm, then kill as many chickens as you want, and sell the feathers for 7each. Also, you kill Cows for their cowhides, which sell for 100each, go to Al-Kharid to sell them.
[Level 50-70]
One method is to kill Chaos Druids at Tavernly Dungeon. You should bring a set of teleport to Faldor runes. When you kill the Chaos Druids, DONT I repeat, DONT ID the unids you get. Each Trip is 25k, and they almost always drop a herb each kill. OR you can go the hard, long way, which requires 38 herblore. First, just ID EVERY herb you get. Eventually, you will start to get rannars, and with an inventory space of 25, that’s 175k right there. Also, you could start killing Hill Giants and take their Big Bones, but this requires a brass key. Big Bones sell for 300-330 each, so you can make a nice profit off of these
[Level 80-126]
Here, you start killing high level monsters like Fire Giants, Greater Demons, and if you feel frisky, you can try out the Tzoks at Karjama. They all drop very good items... eventually, personally, id go for Fire Giants, because they are the lowest. The last one you can try is killing any colored dragon for their bones/D-hide which sell for a pretty hefty price
Lastly, there always the favored, PKing and Staking! Both are self explanatory, and you can win, and lose big. These are both very risky, and usually for the adventurous
Crafting
[Level 10-50]
Crafting is probably the most diverse of the money making stats, theres alot of ways you can make money with crafting. For level 10, you can spin flax into bowstrings, they sell for quite a good price. For the particulary frisky, you can make Vials, and turn them into WFVs (Water Filled Vials) and sell them for 200-250ea.
[Level 60+]
From level 60 onward, you can do a variety of things. You can make Dragon hide armor, green through black, they sell very well.
Mage + Crafting
Mage with crafting is very beneficial. You can make ALOT of things, all of which sell for a VERY nice price. EX. Rings of Recoil sell for 2kea, Str ammys sell for 5kea ect... And when you get to the REALLY high levels you can make Glories 50-60k, AND Furies 4.5-5m. Those are nice
Woodcutting
[Level 10-30]
When you start out, cut regular logs till you have 15 woodcutting. Regular logs sell for about 10 each. Now, start cutting oak logs untill you have 30 woodcutting, oaks sell for a nice profit.
[Level 30-60]
Now that you have 30 woodcutting, move on to willow logs. I suggest that you stick with willow logs, as they are the easiest to sell. Willow logs are usually 20-22each, by the time you have 60 you should have a good 10-11k willow logs.
[Level 60+]
Once you hit the magical 60, you can now move on to yews. Yews are a good nice profit, now at 370-380ea. When you hit 75, you can choose to stick with yews OR move to magic logs, which are about 1.1-1.2kea. Yews cut faster, but are cheaper, but magic logs cut VERY slow, but are more profitable. You be the judge of what you want to do.
Fletching
[Level 75+]
Fletching really isnt really profitable till level 75+, because you can now make yew longs. This really is a complex one, you dont really make money without Woodcutting. But, when you get high fletching, you can buy mage logs for 1k, and cut them into MSB's and sell for 5k Also, when you get 70 fletching, you can do something I LOVE doing. Buy 1k yews, and 1k flax. This should cost you around 400k. Make yew longs sell for 550-600k, repeat. It’s a nice 150-200k profit each time, and you can do bigger loads in the future.
[Mage+Fletching]
Ok this one requires a minimum of 700k, 70 fletching and 55 mage and 10 crafting. First, buy 1k yews, flax, and 1k nats. Then, make yew longs. Alch the longs. 70k profit, plus a load of mage/fletching xp.
Mining
One of the main ways to make a good amount of money. Mine things in large quantities such as iron, coal, or pure essence. These are all good because they mine faster then the higher level ones. I suggest mining these and selling them until you get to rune ore, which sells for 10-12k each ore. Also, there is coal trucks, mine coal, put it into the cart (Requires 37 Agility) Coal sells for 150-200each, so you can make a nice profit off of this
Smithing
Smith the things you get. Start with iron knifes, when you get alot, it can be VERY profitable, as many pures buy iron knifes. You can do full adamant after a while, they tend to sell quite well in f2p worlds, going for 30k. Again, good until rune, I recommend smithing sets of full rune or rune scimms, those are in high demand. Also, although it is a small profit compared to others, if you have 35+ Smithing, you can buy steel balls and turn them into cannon balls for profit. You must have completed Dwarf's Cannon though.
Slayer
[Level 1-30]
For 1-30 slayer, most monsters dont really have good drops.. only pyrefiends have *decent* drops. They drop a good amount of fires and coins, and are only level 38.
[Level 31-64]
There are a variety of things you could kill if your 31-64 slayer. If you have at least 40+, you could kill basalisks. They drop a decent amount of coins, 180 water runes, and 15 chaos per drop. They also drop the occational rune dagger. If you have at least 52+ slayer, you could kill Jellies which drop a large amount of coins each time. Finally, theres Cave Horrors, providing you have 58+ Slayer. Although you must complete a quest to access them. They are VERY good for training, and for drops as well. They drop Black Masks, which are about 250k per .
[Level 65-99]
This is where all the big money is! Dust Devils which you can slay at level 65, drop a large amount of fires. They drop the occasional dragon chain.. but this is very rare. There is a nice range spot for them, but remember, bring a face mask! Gargoyles are also very profitable to kill, providing you have 75+ slayer. They drop granite mauls, and other granite items. Spiritual Mages are for people with 83+ slayer. They drop dragon boots, which are now 330k a pair. They are located in the God Wars dungeon. Abyssal Demons are self explanatory, they drop abyssal whips, and require 85+ Slayer. And Lastly, we have Dark Beasts. They require 90+ Slayer, and drop..the Dark bow.
Runecrafting
[Level 1-43]
I dont reccomend buying your own essence if your trying to make money, untill 22 runecrafting. From there on, you should rune craft airs, as rune essence is 25 each, and airs are 10. ( 3x10 = 30 ) When you hit 35, I reccomend you use the abyss. For help on abyss running, please refer to the section after this. Beware of reverant beasts if you are abyss running though !
[Level 44-99]
There really is no "in between" runecrafting. Anyway.. once you hit 44, you should start to runecraft Nature Runes. Even with buying 1k pure essence, you make a 250k profit an hour, provided you have pouches. (explained in the abyss section) Once you hit 54 you can choose to go to law running, but personally I prefer keeping with nature runes. Then, once you hit 64, you are able to make death runes. Again, I still reccomend staying with nats but hey, whatever floats your boat.
Abyss Running
To use the Abyss, you must first talk the the Zammorack mage, located at level 5 wild at the bend of the edgeville river. From there, you must do a mini quest, which I am too lazy to talk about. Anyway, after you complete it, you get a small pouch and 1k rune crafting xp. Horray! Now, you can start abyss running. You must bring a glory amulet, the highest dragon hide you can wear, and your essence. Enter the abyss, and enter the middle area with whatever skill you want, if you choose to mine, bring a pickaxe, wood cut an axe etc. Also, you can kill abysall creatures for abyssal pouches, the higher your level the bigger pouch can carry. There are four types of pouces, small medium large and giant. They require 1, 25, 50 and 75 runecratinng respectively, and they hold 3, 6, 9 and 12 essenc per.
Fishing + Cooking
Cooking and Fishing go hand in hand, so I'll put them together.
[Level 1-40]
Fishing really isnt good till level 20. From there, cook and fish trout until your level 35, then start fishing tuna. Once you hit 40, start fishing lobsters, they sell for a very decent price, and after you get the levels, fishing becomes obscenely fast.
[Level 40-99]
When you hit 50, you can continue to fish lobsters or move on to swordfish. The downside with swordfish is, that you also catch tuna along with swordfish.. but its your call. Once you hit 62, you can fish monkfish, providing you've finished Swan Song. After you hit 76, start fishing sharks OR keep fishing monkfish. Monkfish are cheaper, but they fish faster, but sharks fish slower but are worth more money. You be the judge.
EDIT: I am NOT done, I'm not even CLOSE. But, post any suggestions you have here in a way I can improve/add to my guide.