If someone wants to find it, almost sure it would check personal information like family names, birth dates, or specific dates with relevance. Places of birth, or names from institutions, children or a mixture between them with other data.
Thus the best method to select a password is to never use personal information that in some way is available.
Another common mistake appears in specific combinations with the keyboard. Those ideas of using three in a row, diagonals or alike figures come as another aid to discover a password. There are software applications with the ability to find patterns of this kind, or to test simple numeric and letter combinations.
Good reasons to forget those techniques that help memory, but they are a hole in the security door of your home. With a good password, there's no need for more and to change it, it would be as easy as to add a single character in the middle, the beginning or the end.
The best advice in our opinion is random numbers and letters, like a telephone number of three blocks of numbers with some symbols in between. For instance 845-820-805, helps memory because it starts always with an eight and the second digit is always even and diminishes by two units. And then a random word, like "blue" but making it to lose its "dictionary" property. "BLLUEE" doesn't appear on it. 845BL820LU805EE. After, a symbol in between like "_%", makes it a password with an acceptable degree of security, where longer means better because to break it in brute force terms, with software, it would need much more time.