I've only done rezoning and watched a number of people gone through the process here in St. Johns County, FL. OF course every county is different but I think the overall strategy should be similar.
You should be able to ask the staff at planning and zoning department and they should be able to tell you the general procedure and the cost.
Here in our county, you submit an application, the county will handle the notification of neighbors within 300 FT radius and advertising (applicant pays all costs). They will hold public hearings, the applicant can attend to make the case, all the neighbors can attend and object, the county commissioners will vote on it in the end. Rezoning cost about $3000 and it's not a guaranteed process. So unless there is a huge upside, most people don't do it. You never know what your neighbors will say. I've seen a number of cases where the neighbors just disgruntle and not like to give the applicant nicer things for very selfish reasons. And they don't care if you are doing something for the greater good. You can run a neighborhood campaign and see if you have the support. It takes time and effort if you don't want to just roll the dice.
Things to consider: look at future land use code and the property use in the neighborhood, applicant has much higher chance to get the rezoning approved if it's conforming to the future land use code and to the use of the neighborhood. I.e. rezoning a commercial property into a residential property where in a residential neighborhood.
Applicant will have almost no chance if the applicant is against the future land use code non conforming to the overall use of the neighborhood.
True story: I had a client purchased a 4plex in a city. The 4plex was a distressed property and left vacant for over a year. The city has a policy that multifamily properties in single family residential area, if left vacant for over 6 months will automatically revert to single family (lost its grandfather protection). My client bought this property with high confidence that he's making the neighborhood better, fixing it up and making it a nice 4plex (current setup with 4 utility meters). And the number doesn't work if it's just SFR. He needs a variance to revert the status back to multifamily. He thought he had lots of support based on his conversation with the planning and zoning staff. When came to the hearing date, he showed up and ready to knock it out of the park and to his surprise, almost the entire neighborhood was against his plan. And they would rather see a distressed, property stayed abandoned, than my client improves the property and make it four units for 4 families. So the variance (similar to rezoning process) was rejected. He couldn't make the number work and sold the house at a slight loss. Over two years, I've seen that house being purchased and sold by multiple people and still sitting there as a piece of cr*p today.
Hope this helps.
