I did Nitrox first. It does help you decide if you want to go the technical route. IF you want to take pictures and don’t know a lens from a viewfinder, U/W photography maybe for you. If you haven’t done alot of Boat dives, the Boat Specialty may be the way to get a reduced rate on a couple of Boat dives. the list goes on and on. You can look at it from Strengths and Weaknesses. Go for what you are interest in or what you don’t know alot about but want to know more. With an Instructor, You know that you will get good training. With a divebuddy, You may just get what he or she thinks is right, not what is doctrine. Then again this is just my opinion. And as far as fast, I would go for quality, instead of quantity.