These are very easy. You can fail by either letting your client die or kicking the bucket yourself. Neither of these will probably happen, though. Your client is more fragile than you, but if you get attacked, the enemies will be gunning for you, not him. Just stay alive, keep your guy out of the crossfire, and know where you're going. Finally, note that bodyguard jobs are one of two types where you are paid by the client, not by the Johnson.