My policy is be friendly and patient. Also, let them win the first game but point out how their moves could have backfired and what I could have done to counter what they did. Some accept it, others insist I actually go through with what I could have done to see how it works. I like the latter group as they are usually very dignified in accepting their losses. I also tend to offer a lot of advice during play (reminders about reach and free strike threats, etc...)...but I tend to do that anyways unless I'm in a release tournament.
So yeah, I treat them like any other player really, except I'm not trying to beat them in the first game or few. After a month or so (depending on how many games they've gotten in), they become just like any other player to me.