In response to AsTr0GiRL:
Riddler 1: I have no colour, though there may be darkness
within.
UNIVERSE-------nope
Riddler 2: Of all your possessions, I am the hardest to
guard.
You-------haha, when i say "u" to secret, i mean the answer is
'secret'... 
...so your answer is
wrong.
Riddler 3: Alive as you but without breath, as cold in my life as
in my death, never a thirst though I always drink, dressed in a
mail but never a clink.
POND------wrong
Riddler 4: They follow and lead, but only as you pass. Dress
yourselve in darker black, and they are darker still. Always they
flee the light, though without the sun there will be none.
SHADOW------yes
Riddler 5: The life I lead is mere hours or less. I serve all my
time by being consumed. I am quickest when thin, slowest when fat,
and wind is the bane of the gift that I bring.
CLOUD-------wrong
Riddler 6: The man who invented it doesn;t want it for himself. The
man who bought it doesn't need it for himself. The man who needs it
doesn't know it when he needs it.
COFFIN-------yes
Riddler 7: The more there is, the less that you see. Squint all you
wish when surrounded by me.
DARKNESS-----this time, correct
Riddler 8: I am free for the taking through all your life, though
given but once at birth. I am less than nothing in weight, but will
fell the strongest of you when helded.
BREATH-----yes
Riddler 9: Lighter than what I am made of, more of me is hidden
beneath, I am the bane of the mariner, a tooth in the endless blue.
Speak my name.
ICEBERG-----yes
Riddler 10: A spirited jig it dances bright, banishing all but the
darkest night. Give it food and it will live. Give it water and
watch it die.
FIRE------yes
oddly enough, your score is 6/10 also... 