Starting an Empire
Now I am not going to tell you this is easy as nothing ever is, but this will give you a general idea of how to make alot of money on runescape. I do not promise to make you it over night but this does have some good ideas to make money in the game.
Now I will assume that you are level 1 (Just starting) and you are on the free servers, (making money on the members server are alot easier but that is because they are pay servers). If you are used to the game then you may want to jump to the later chapters.
Now at level 1 you have a long way to go to make millions but everyone has to start somewhere, so let us begin. First we want to go and chop some trees, now although there are trees in lumbridge and draynor, at level 1 there are also monsters so I suggest running over to Fallador (West Bank), just outside the north entrance there are a patch of trees that at level 1 are perfect to cut and there are never anyone there. You can bank your logs at fallador (West Bank) and continue cutting trees.... Do this until you have about 1000 logs, you should be quite a high level lumberjack by this time about level 30 or so, now you want to sell these 1000 logs to people at Draynor Bank so head over to Draynor and sell, sell, sell. Make sure they are Noted (there is an option in bank to withdraw Noted or not). Sell these for 10gp each (yes i know this doesn't sound alot but its 10,000gp for you).
Now you have 10,000gp invest in a better axe and go chop down oak trees, once you have 1000 oaks move up to willow trees ect ect.
Please remember whilst you are cutting trees on the free worlds to talk to other people cutting trees and make friends with them as later in the game you may need these friends to make you more money.
Make about 100,000gp doing this and levelling up your skill and now you can start buying from other characters, start by asking the people you have met whilst cutting trees yourself, and ask if you can buy their wood from them.... Remember to buy low and sell high. Buy for about 7gp per log and sell for 10-15gp per log for normal trees. Buy oak logs for 10gp and sell for 20gp. Buy willow logs for 25gp each and sell for 35gp each ect ect
Employ people to Buy logs off, then sell them in banks (Now this is a slow process but keep persisting and it pays off)
Once you get to about 300,000gp you can either keep with logs and keep cutting your own logs or go to another area like mining or fishing.
With high levels of logging you can cut yew logs which sell at 250gp each.
Mining
Now if you have followed the above steps you should have alot of money now to invest in ores and coal. Coal is the main seller in runescape as it has alot of uses for higher players so they will pay more for it.
Buy coal from people that are new to the game for about 100gp each and then sell it between 150gp - 200gp each for a quick turnover in profit. (Trust me new people will sell for 100gp each as they think they are making alot of money which they are, but they don't know your making more on it).
Also another one under mining is rune essence, this can be a big money maker in high quantities as to buy 1000 rune essence you can get it for 10,000gp which is 10gp each, then collect about 10,000 rune essence and sell it to a rune crafter for 20-25gp each but these prices can only be achieved with amounts of 10,000 rune essence or above.
Fishing
Fishing at low levels doesnt make any money at all as people don't really buy the fish, once people start selling lobsters and above is when you get the buyers but still there isn't alot of business in it. For new people I wouldn't have even suggested it but for an all round money guide I had to make some reference to it.
Rune Crafting
This can be a very good way to make money with the right management, Buy rune essence for 10gp each as I mentioned above then employ rune runners to run the rune essence from the bank to you at the altar. Air runes and Mind runes are the best to do on the free server and as your runecrafting goes up you get more runes for your rune essences. You can then sell air runes for 20gp each and mind runes for 10gp each but as i said at higher levels you can buy 1 rune essence for 10gp then craft it to say a Mind rune and get 5 mind runes for 1 essence the sell the for 10gp each so you are converting 10gp into 50gp. You can also pay your runners with the runes say give them back 1-2 Runes per essence. Trust me you will still be in profit and it wont take you long to convert 10,000 Rune Essence to about 30,000- 50,000 Mind or Air runes. Also after a while your runecrafting level will go throught the roof and you will be able to convert 1 rune essence into 11 Air runes and 10 Mind runes so you see it can be quite lucrative.
I give you these as a tip on how to make money, I do not guarantee that you will make it overnight but I do guarantee that after time you can accumulate alot of money. I suggest selling Mind Runes and Air runes in the wizards tower south of Draynor as you get alot of Players attacking the monsters in there that don't want to leave and ask people to run to get more runes for them.
I am presently a (free member level 89) that has used the last option of Rune Crafting and have accumulated a wealth of 47 million gp in 3 months. So it is possible with determination, and patience.
If you just keep doing all these options and making new friends and asking them to work for you then you can make as much money as you will ever need in the game.
Lobsters and above are best sold in the Duel arena north east of Al Kharid (there are always duellers needing food there, just don;t be tempted to have a gamble on you PK skills).
There are many other ways to make money in runescape which I haven't really looked into and couldnt really say anything about them other than they are (Cow hides, feathers and wool).
V good :D