In addition to HalfFull's helpful advice, I will add the reality that public city council meetings are merely the culmination of all of the lobbying/deal-making/decision-making that has already taken place behind closed doors. Yes, you will be able to see how the various council members vote at that open meeting, but thinking that your comments will change their already-decided votes is...unrealistic.
I have taken the oppportunity to speak at City Council meetings in regard to issues that are not up for a vote that night, in the hope (perhaps, in vain...) that my comments might help to inform council members, and--possibly--influence their decisions at some point in the future. However, on the night of a city council meeting, all of the decisions have already been made, and their voting at that public session is not going to be altered by any comments that you might make that night.