Before you submit a review, take notice of these things;
If you try to flag to me after making my game miserable pretty much the whole time before the flagging, don't expect me to accept it, especially if you took a whole lot of my territories just beforehand.
If you've been a noticable douche (PGA, flagbreaking, excessive foulmouthing or unnecessary insulting, etc.) in any previous games, I will not accept your flag, or if I feel like it, I will return the douchery by keeping silent and letting you jump to the conclusion that I've accepted your flag (honorable players, this won't happen to you).
I do not verbally flag unless asked. I do, however, accept verbal flags if the player seems trustworthy (if I have the time between rounds, I will check the player's reviews before accepting a flag). In case I accept a flag, I will inform about it. If I don't answer, do not draw any conclusions whether or not I've accepted your flag and then start complaining about flagbreaking, because it didn't happen.
System flags are worth more to me than verbal flags, unless the system flagger tries to ninja-flag his/her way to the top, or has been an incredibly annoying jackass.
If you've flagged to me, and you attack me even once, I count that as flagbreaking, whether or not it was intended or not. I've had one too many players disconnect me by "misclicking" and then betraying me. Also, if I'm in the lead, you're flagged and fighting for places 2/3 or something similar, do not use my territories to make yourself bigger against the person you're fighting; Counts as flagbreaking.
More may follow.