Persoanlly, I would use a combination of words, numbers, and in some cases symbols relevant to me... like so -
My lucky number? 7.
my favourite number? 64.
My name, shortened? Adz.
When was I born? 1995.
month/day? 7th of April
Dogs name? Benji.
Now, by placing these in a memorable order, you can get...
7adz640704born95benji7
but wait, there's more. hold down shift when typing this?
&ADZ^$)&)$BORN(%BENJI&
lo, the numbers are now symbols. looks a lot more complex.
Feeling like you're memory is running good? Why not add the last 3 digits of your phone number, the initials of a school, perhaps, and your name converted into numbers? (ie Adam is 1 4 1 13, basing A= 1 b =2 etc) and alternate your shifting.
last 3 digits of phone? 826
school initals? AVS
NumberName? 14113
mix into start...
7adz640704born95benji7826avs14113, before shift.
Now, say if i hold down shift every 5 characters...
7adz6$)&)$born9%BENJi7826aVS!$!13
is a 33-letter long password with uppercase, lowercase, numbers, and symbols.
I myself have a similar password (ie the structure) on most things I keep secure. by remembering number chains I can add vast complexity to it and end up with a combination of ucase, lcase, numbers and symbols, I'm pretty sure you're going to be safe.
Note: Although my password structure is similar to the one above, the characters themselves are completely different, so don't bother trying to log in as me XD I have written this as tips that I myself use and trust.