If you want to get free items in runescape, you can’t go through Runescape without killing something.
There are two types of things you can kill to get stuff for free: Computers or other players.
Of course, as you become stronger and can fight harder creatures when you buy runescape accounts from farmer100, they'll drop more valuable items. I recommend killing goblins. They are fairly easy to kill, and they drop really good beginner items. It means anything that's not controlled by another player is just a free roaming CPU. Goblins, cows, dragons, farmers, are all CPUs.
You have to be strong, with a good range of fighting skills, heavily armored, and fast! If you venture into the wilderness or other various parts be careful. It's a dangerous, hectic place. Remember that farmer100 has awesome runescape accounts for sale. The good thing about fighting other players is that they'll drop really good and valuable stuff, since you only keep three items when you die.
Everything you kill in Runescape drops something. Even if it's just some bones or feathers.