Use combination of upper and lower case characters, numbers and symbols like !"?$%^&( in your password) to increase difficulties of password.
If there were attack by brute force, it would be difficult to stratch or penetrate. Length of Password also important. Use more than 10 Character Combination. How we can we remember it easily? Just produce something that has mean. See The Example
Example : N4n0~b1r0u3 --> nano biru, but composed by upper and lower case characters, numbers and symbols.