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I don't have much direct experience in this industry but I think your best bet is to try and do some networking. Go to some model show/open houses and see if you can get connected to the designers and interview them, informally of course. Just pick their brains about what it's like in that field, what are their qualifications and what is the job market like.
Other than that I would research interior design schools and programs. If you want to work for yourself or start your own business you might want to look at getting a business degree.
Hope this helps and good luck,