I know it may sound hard or impossible, but these tips can make those wannabe 8-year-old "haxors" cry.
Make our password a series of random numbers and/or letters. For instance, "Iamcoolhahaha" is much easier to guess then 1564nhgf564. Now, this might be hard to remember, but write it down somewhere at your home, in a safe place.
Change your password, say, once a month. That gives you enough time to get used to your new one before having to change it. Each time, write it down, in case you forget.
Never, NEVER give your password away. Not friends, not family, not Santa Clause or a "Jagex programer". These are common scams when on the internet, people will try to tell you that they are Jagex programmers, know their way around the coding, and can give you all kinds of things ect. NO! It is a web of lies, all of it.
Any site but Runescape.com
is not to be trusted with your username and password. No exceptions, at all.
Make your recovery questions easy to remember, impossible to guess. For instance, make a question, but give a completely unrelated answer to it. Like:
#1
Answer:Hi
#2
Answer:my
#3
Answer:name
#4
Answer:is
#5
Answer:Bobby!
This will send hackers crying!
Ignore anyone in-game who asks for your password. Not even Mods will have a good reason to know it, other then to hack you. Even Jagax staff members won't need to know it.
And, last but not least, set a bank pin. Make it a number impossible to guess, like a random number. That way, even if someone DOES get to your account, it wont be much help at all.