The more competitive the friend, the better it is.
On one of my friends first game, we had a 4 way 400-ish point battle of just infantry between blood angels, space marines (me) necrons, and tyranids - the new player.
Instantly I could have raped him with my 4x heavy bolter devastator squad, but instead of firing at his genestealers I just fired some normal bolter rounds at his hormagaunts, kind of warning shots so he wouldnt come for me to soon.
Soon mephiston came in and cleaned up my terminator squad before some sternguard told him what for and killed him with plasma, and then the new tyranid player came in (the necrons were dead to the last) It ended up being between 2 genestealers and a sternguard sergeant with powersword, and the 2 genestealers clearly took the cake.
So the TFNG won and it was kind of a confidence booster, although
Id never let him talk smack about his win against me,
Id instantly challenge him to a duel and crush him
I guess if you beat them first game, try to lose the next game? But dont make it obvious. Or field stupid units.