The general requirement for passwords is that they should be a minimum of 8 characters - letter, numbers, upper letters and symbols. The longer the password is created using this guide, the more secure it is. A password of 8 characters is extremely hard to crack if it's correctly created.
For a successful password you can use the following template: J0hNsm1!2t3_$3. A password of this type is very hard to crack and any system that you use will gladly accept it.