The importance of extra training after graduation
If you are planning to work as a business consultant you are going to have to have skills that go far beyond those of a college graduate. You will need to be able to offer clients something that they can't get from within the company, this requires a great deal of training after graduation.
The big reason that you would need extra training after you have graduated from college is that for the most part college provides you with very little training that is directly applicable to being a business consultant. For example if you graduate with a business degree you will really only have the skills required for an entry level job, you can be sure that companies that hire consultants want somebody with more than entry level skills. A lot of consultants find that a liberal arts degree is more useful career wise. This is probably true but since it offers no direct training in business it will be necessary to get training in the field.
The other big reason that you would need additional training is that in most cases when a business hires a consultant they are usually looking for them to bring skills that they don't already have in the company. Since business majors are a dime a dozen you can pretty safely assume that the company already has people with the same skills that you got at college. Obviously there would be no reason to hire you as a consultant if that is the case. You need to offer some sort of advanced skills.
It is clear that you are going to need additional training after you have graduated from college if you are going to be a business consultant. The question is just what kind of training do you need? In general you will find that you have the best chance of being successful as a consultant if you can develop a skill that is in short supply. Something that is highly specialized and which takes a great deal of training to become proficient at would be the best. Take a look at what skills the consultants who are getting hired have and look into learning one of these.
The other big area of training that you will want to get if you are going to be a consultant is on the so called soft skills. You want to be an expert at things like team building, and communication. This will not only make you much more effective as a consultant but it will also make you more in demand. A lot of companies are finding that they have the technical skills already but that they really struggle with the soft skills and will often bring in a consultant to help develop them. If you can help them with things like team building you will find that you are in high demand.