Do not reveal your password to anyone. Password is used only to log on in a particular place. Noone and nowhere else can figure out what your password is.
If you absolutely need to provide access to someone, change the password to temporary one. Check whether the password recovery options are set, and whether you remember them. As soon as possible, restore your password or set a new one, unknown to the person you have provided access to your account.
Do not send passwords via e-mail. Such demands are attempts to swindle the password. If such a request actually came from someone associated with the service, resign from this service, or explain the situation with someone competent.
Do not store the data on the recovery of passwords online or on a computer connected to the network. For this purpose, use external memory (CD / DVD, MemoryStick, SD memory card).
If you store your passwords on a card or other storage media, make sure to protect it. Do not leave visible, do not share, do not say where it is kept, do not give for safekeeping.
Try not to use national accents. Most systems should deal with them, but sometimes they may cause trouble.
Do not begin the password with the initial letters of the alphabet. In some cases, it will make the procedure of guessing your password take more time.
Do not share your computer to others, and certainly not without your supervision.
Do not leave your computer unattended.
Regularly use antivirus and firewall, and look after their updates.
Do not open or run files whose origin and effects of actions are not sure.
Follow the recommendations of the operating system and browser manufacturers.
Install the recommended updates for the programs you use on your computer.
Illegal software can be modified and after you install it, operate transparently to your detriment.
Do not use publicly available computers to perform the operations that should be known only to you.
If at the place where you use a computer, surveillance cameras are installed, use the keyboard and monitor in a way invisible to them.
If you are disposing of a computer or a disk, make sure the proper removal of data (simple "delete files" is not enough!) or destruction of data media.
Be especially careful about mailbox you are using with different accounts. It is used to change or reset your password and your data. Therefore the loss of control over it and outsiders' access to its contents may be most painful.
Do not use a single e-mail address for everything. Use one address for the key services (eg. banking). Use another e-mail for contacts with family and friends. Use a different address for newsgroups, forums and other less critical services.
Use the "Sign out" funcion as soon as you finished what you had to do, or if you leave your computer.
Do not use unencrypted wireless connections to the internet, if you want to sign in somewhere, send or receive sensitive data.
For your own and others good, inform administrators / owners of the systems to which you log in, of any suspicious situations.
Do not publish in the network your personal data (name, email address, IM number, etc.), except places that really need it and ensure its proper protection.
When you enter your personal / contact information somewhere, think it over and consider the consequence of making the data public.