What characteristics make a solid brain wallet?

[EccLipSe]

when using correctly spelled words and numbers as a separate element, your password would be easier to crack

try
america banana cast dominican equator frenchfry guacamole honduras 12345678
as
4m3r1c4 64n4n4 c45t d0m1n1c4n 3qu4t0r fr3nchfry gu4c4m0le h0ndur45 12345678

and if you want something to remember long term.. choose a book and a book page and line and the use that as your passphrase were some of the letters are made into numbers

Eg

c4ll m3 15hm43l 50m3 y34r5 490 h4v1n9 l1ttle 0r n0 m0n3y

who would of known knowing 1337 would pay off  

good trick for an easy to remember strong password

Someone watches Person Of Interest .

[mccoyspace]

6. Burn truecrypt traveler exe, bitaddress.org html file, encrypted file, onto a CD/DVD.

I think optical media is only expected to last for 10 years or so before the plastic starts breaking down. Some USB sticks are also only guaranteed to retain their data for 10 years (or less!). It's something to keep in mind if you are going for very long term storage, physically written down/engraved seems to be the safest bet.

I just finished migrating data from over 50 CD-Rs that we're all going on 20 years old. They were all OK. FWIW.

[Kouye]

One easy trick I use is to take a common phrase you might not forget.
Then replace, in all subsequent words, any occurrence of character appearing in the first word with 'a', 'b', 'c', 'd', etc.

For example:
One must be poor to know the luxury of giving

becomes:
One must ba pbcr td kefw thg luxury hf giviig

Which has >200 entropy and is basically impossible to crack, yet pretty easy to remember (one common phrase+one transformation method).
Of course, the transformation method is up to you, this is just an example, but it needs to remain easy enough.

[mpfrank]

Well, personally, I don't want to have to trust any computer-based RNGs, and I also don't trust any naive notions regarding which methods for generating/obfuscating a short-ish passphrase are "sufficiently obscure" yet "easy to remember," so instead, I use Diceware to compute a truly random, 10- or 20-word brainwallet passphrase, calculate its Bitcoin address on an offline computer, print everything out in multiple paper copies which are safely hidden away (since I also don't trust any digital media to stay readable), and, for the coldest cold-storage wallets, never, EVER enter the sensitive data (passphrase or private key) into ANY online computer.  If the passphrase is 20 words long (100 die rolls), this method gives you a full 256 bits of entropy, which is as secure as any Bitcoin address can be, but a 20-word phrase is much easier (in a pinch) to memorize, or to read over the phone to someone, than a random string of letters and numbers would be.  My full method is described at:

http://minetopics.blogspot.com/2013/03/ultimate-bitcoin-security.html

[Shallow]

Really long memorable phrase

[phillipsjk]

Which has >200 entropy and is basically impossible to crack,

Log₂(200) is ~ 8.