K2 should not be your first 8000er. In order to have a fair chance of success and survival, you need prior practice. For Everest, good starts are Cho Oyu, Lhotse, Shisapagma, Aconcagua, MountMcKinley or GII. For K2, a great experience is gained at Everest, Makalu, Manaslu, Gasherbrum 1, Broad Peak and the likes.