My Philosophy with bitcoin is that it could end up worth $100-000 - $1M per coin, but there is a real chance it will be worth zero in a years time.
I put in enough that I won't kick myself if 1BTC would let me buy a house a few years down the track, but little enough that it ends up worth zero I have no regrets.
Its definitely requires a long term approach - sit and hold or dollar cost average. Be totally prepared to lose the lot.