This xkcd comic has been instrumental to me.

I wrote a command-line utility a couple of years ago that I use myself regularly to generate secure and memorable passwords

https://github.com/ctsrc/Pgen

With this tool you can also see how many bits of entropy the passphrase generation settings you are using will result in.

For example, generating a 5 word passphrase using the long wordlist

    pgen -l -n 5

will yield a passphrase like:

    joyous embolism outsider evasion mashed

And when we ask the tool for the entropy with these settings

    pgen -l -n 5 -e

it will tell us:

    Current settings will create passphrases with 64.62 bits of entropy.

And hey, if you have reason to not trust the randomness capabilities of the program or your computer guess what :)

My program supports the use of physical dice to generate your password.

Have a look, try it out yourselves :D

https://github.com/ctsrc/Pgen