If you can use special characters in your password, then you would have a very strong password, but if you can’t, then your password won’t be very strong.
A strong password should be made by using upper, and lower case letters with numbers. Depending what the password will be used, for will determine if the password should be short, or long. Obviously if you make a long password then it will be stronger, but it depends where the pasword will be used.
For example:
You could have a strong 15 character password consisting of upper, and lower case letters with numbers, and it depends where you use this kind of password. Because in some places your limited to a certain amount of characters to make a password.
If you have a hard time to remember a password, then write your password on paper, and then hide it in a safe place where you can remember where it is.
You can get more info on this blog post.
