I definitely recommend some group classes at a good dance studio that has professional instructors if possible. The reason is you get to come early and stay a little late and watch the professions or real good amateurs practice and teach. I don't mean to speak ill of YMCAs and College ballroom clubs. Quite often those group classes are taught by excellent teaches and are very good. I only mean to say that you will in general see much better dancers at a studio. If you have any talent, you most likely will quickly surpass the others in your group class and may get bored or lose interest. When I was starting I found the dance studio to be very motivating.
Think of it like learning to play golf. Sure you can go to the local driving range and hit your practice balls along with all the other learners, but wouldn't it be better if you could go to a range where better people than you practiced? One can learn a lot by watching.
Having jumped through silver and danced in some Pro-Am opens, I can tell you that technique, form and posture are much more important then you may believe. Steps are relatively easy to learn. You can tack on one or two a week in a snap, and it won't take long until you can dance a two minute song at a dance party and never do the same two steps in sequence. However, if you learn the steps incorrectly, then even the Pros won't be able to follow you and you'll look terrible.
Private lessons are a necessity. You should ask for a syllabus and keep track of the steps you learn. Without a game plan, goal or target, you may just wander through the dance world. Mentally go through the steps during the week to get your brain thinking about the steps. You can really speed up your advance if you practice the simple exercises at home like your posture, your lowering and compression, moving your torso, cuban motion etc. DON'T just go to your private lesson and then work on the form if you didn't practice at all on your own since last time you were there. You should do your homework between lessons!
Good Luck