DO IT! The show is different from the books. As far as importance of certain characters and what not. But you'll like the books they just keep getting crazier.
The show did a good adaptation, I understand why they changed what they did for entertainment value.
Reading them won't spoil the show too much, I'm still on the edge of my seat when I watch the show because I have an idea of whats going to happen and then sometimes they take it in a completely different direction. The first season did follow the first book nearly to a T though.
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