Raeker wrote:
Change your password to something that can't be easily guessed. Do it in a different language that isn't English if you have to, and if you can't remember the password then make sure it's written down and not somewhere on your computer.
Make sure you're using the Mobile Guard Authenticator. This ensures that your phone is requored to log in - although there are some tricky ways to get around the method. Also make sure that your e-mail has a different password - once again secure - from your Steam account.
Most secure passwords are something such as a bunch of random words put together, hardest for a bot to guess.