Let me try to provide some practical advice. If you want the fastest learning curve then you can start with private lessons but that can be expensive, and who would you choose? And if you have limited time to invest where should it go? I am on the board of a ballroom club and have been on the board of a West Coast Swing club and here is what I say when I am asked the same question by a beginner. Use the Internet and search for ballroom classes in your area, look at their calendars for dates and times and locations that fit you. Start with beginning Waltz and East Coast Swing classes, or maybe something like Cha-Cha instead or in addition to. Each class might be $40-$50 for a monthly series. This is a physical activity so the best metaphor I know is "you want to play mixed doubles tennis - you need to know your part and you want a good partner". Don't expect much from the leaders in these beginning classes, just learn you part. There are many fine Arthur Murray and Fred Astaire studios but I suggest you look for a owner/operator ballrooms. Get a feeling for the teachers and then maybe think about the sparing use of private lessons. Dance well.