The Slytherin house is one of the most misunderstood house in the books of Harry Potter. Slytherin students have Ambition, Cunning and Resourcefulness. They also value tradition and are born leaders. It is a plus that they are sexy too.
There are many of mixed blood purities in the house. Snape and Tom Riddle were both Half bloods as was Pansy's best friend. There were also a few Muggle borns as mentioned in the DH book.
Slytherin has long since changed from being a pureblood haven and only dishing out bad wizards.
Notable good wizards from Slytherin are Andromeda Tonks and Horace Slughorn.
Slytherins also love hufflepuffs as they are fluffy.
Slytherins are as smart as Ravenclaws but darker, as powerful as Gryffindors but think before they leap and are loyal to their family and friends like a Hufflepuff.
Never tell a Slytherin they aren't a true Slytherin.
Every Slytherin will be led to greatness.
Merlin was a Slytherin one of the greatest muggle rights activist.
Slytherin people are so freaking awesome
The Slytherin dorm is under a lake! That is like a free aquarium without having to pay a stupid fee. Put your finger on the window and see if a fish follows it.