My first piece of advice is to make sure there is another member of managment in the meeting. This is always a good habit to get into. Secondly, make sure you have valid points to substaniate and illustrate how this person isn't doing his/her job. Chances are he/she already knows this and will be a pisser about it. My experience is the more hostile, the more the person knows they are up to standards. I would then have a improvement plan ready to go. Give he/she so many days/weeks etc to improve. At the end of said period, another conversation takes place. At that meeting, performance is reviewed. If everything is ok, keep an eye on the person and carry on. If not, then there needs to be a stricter plan laid out. Maybe more one on one training etc. Hope this helps.