I was initially not an FPS player myself, and have played few to name. Borderlands 2 and Halo Reach were my training programs. I only got decent at FPS because of weekly game sessions with my friends, and not merciless online communities. I understand the frustration of where you come from, and hope the cooperative campaign will give you key skills that you can implement in PvP, should you ever attempt. Thoroughly wish you excitement.