The one thing any protest should avoid is any encroachment of the pitch, which potentially could endanger those who actually are entitled to be on the pitch
(players, officials, manager/coaches, physios etc).
NO projectiles of any sort (paper planes, squash balls, coins, oranges (those were the days), beachballs etc etc). Supporters as well of course. There are potential dangers to anyone who's entitled to be on the pitch, and any supporter in front of projectiles of any sort are vulnerable to freak injury.
Any such action will be viewed & reported by the media and will detract from/negate the impact of any protest.
Red cards yes. Mass walk outs (temporary @ e.g. 19: 04 for say 11:20 minutes (reflecting how many years we've been around)). Co-ordinate this temp. walkout with getting as many as possible away fans to sing the "Allams Out" chants/songs etc in a message of solidarity during this temp. walkout.
The TV cameras & commentators will capture all of this & it will be globally visible to all.
Don't **** it up with reckless activities please.
EDIT: If anyone knows any of the City players personally, it may help if they gave them a heads up explaining the objetive of the protest and it is in no way directed at them.