Many people have misconceptions about the right to assemble in the form of a protest. In the media, we often see protesters arrested by police or, worse yet, the group devolving into a violent mob. Yet, peaceful picketing and protesting is an essential part of democracy: the fruit of the right to assemble and free speech. What you need to know is how to protest safely and within the legal system.
You should know that your right to assemble is protected by the First Amendment: "Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof; or abridging the freedom of speech, or of the press, or the right of the people to peaceably assemble, and to petition the Government for a redress of grievances."
That being said, North Carolina allows each county to create ordinances relating to picketing and certain rules must be followed. We will use Mecklenburg County as an example.
The first thing of note is the size of the protest; in Charlotte, if you expect the protest to contain fifty (50) or more people, then you must give notice of the intent to picket to the CMPD at least 48 hours in advance. You are not asking for the right to picket. This notice is used to allow police officers time to plan for increased traffic in the area. The chief of police or designee should give a "receipt of notice" which you need to show to any officer that asks for it during the protest.
Secondly, you need to know where to protest. In the Picketing Ordinance of Mecklenburg County are listed several "city-owned areas" where one may organize a protest (provided that the property was not previously reserved for private use such as a festival) as well as any public area such as a sidewalk. More importantly, you cannot protest on private property (without permission), on a median strip, or at a location, directed, focused, or targeted at a particular private residence.
Next, your protest should not disrupt the public. This means that you cannot obstruct the flow of vehicular or pedestrian traffic, nor the passageway into any driveway, entrance, or access in general. The ordinance may even have regulations of the signs you are able to use so as to prevent obstruction of any passage. Anything you say shouldn't "tend to provoke a reasonable person to a breach of the peace".
Finally, you should pay attention to related ordinances. Be sure to check up on the city's noise ordinance as well as the handbill ordinance, and follow those accordingly. Naturally the protest should be peaceful and respectful of the authorities. It is important to remember that the police are there to protect all sides and if the picketing is causing "disorderly conduct" then they have the right to disperse the group.