There are broadly two types of advertising agencies, online and traditional. You have not mentioned to open an online advertising company therefore, I am talking about traditional advertising agency.
You need capital for it. The cost of capital is totally dependent on where you want to place your office, how much medias you want to cover like TV, Radio, Billboards, Printed Media etc. It is totally a fake idea to give an exact figure for your budget because your budget depends on your marketing mix and scope of your business. You need a team of people who will work for you to design advertising plans like a creative director, computer designers and talented marketing people. For establishing an office you must have an office on such place from where your associated media people can contact you. You also need a production studio.
You should hire some finance people to handle your accounts. Some marketers are required to attract your target audience. These are the sales people. Moreover, you will not find any legal documentation process for this, however state laws can vary!
You need capital for it. The cost of capital is totally dependent on where you want to place your office, how much medias you want to cover like TV, Radio, Billboards, Printed Media etc. It is totally a fake idea to give an exact figure for your budget because your budget depends on your marketing mix and scope of your business. You need a team of people who will work for you to design advertising plans like a creative director, computer designers and talented marketing people. For establishing an office you must have an office on such place from where your associated media people can contact you. You also need a production studio.
You should hire some finance people to handle your accounts. Some marketers are required to attract your target audience. These are the sales people. Moreover, you will not find any legal documentation process for this, however state laws can vary!