Making millions in Runescape can be hard work, especially if you are trying to kill monsters to get the money. Personally, I believe the best way to making millions in Runescape is hording, but some do not agree. Some believe you can kill certain monsters and sell their drops to make your money. This is true. Greater Demons have some nice drops; occasionally you will get something Rune, and can get a little profit. That is a rare drop, however. It seems some of the best monsters to kill for items are the Dragons.
Kill Monsters to Make Millions
If you are a lower level, you could also kill Moss Giants. Fighting for your money is not the best way, especially if you are a mage or a ranger. The money you will make is just going to cover your costs in arrows or runes.
Therefore, if you are going to kill monsters for money, you will defiantly want to use meelee. However, even with meelee you spend money on potions, armor, and weapons. To really make money, you will need a high level so you can kill monsters like the dragons, and get some really pricy drops. Of course, the only way to get that high level is to train.
So unless you are of a high level already, I suggest getting out their and training. The higher level you are, the higher-level monsters you can kill, and the higher-level monsters you can kill, the better drops you will get. This means more money for you. Happy Playing!