The first half dozen lessons are the most important. Piano is a hobby where one can easily injure oneself if you don't use the proper posture and technique.
Unfortunately, piano is also a hobby where a lot of boredom occurs before one can achieve one's goals. For example, playing a particular piece you enjoy may be several years of practice in the future.
Also unfortunately, most teachers follow a strictly classical training regime, instead of accomodating the different style required to play popular music. If you pick a teacher at random from the professional guild in this location, you will find someone with classical training that can run your through a standard method, including the deadly (but necessary) exercise books. In this location a good teacher will start you in Edna Mae Berman (or Schmitt, where I started). I understand in Europe people tend more to use Hanon. If you don't do the exercises, you won't learn proper finger techniques. For example, Schmitt is particularly good in developing skill at using fingers 4 and 5, or in my case, my injured finger 3.
My teacher took me through classical chord theory books, which did not involve ear training, which was totally useless for playing pop songs. I had to pick up guitar (which my body is not suited for) and back the techniques into the piano, to understand the use of chords and lead sheets for playing pop music. This happened in my late forties, instead of in my teens when I asked the teacher to help me play a pop song I was enthused about. I hope you find a teacher that is more into current music than mine was, but they are rare. I can't find a pop techer in this county now at all that doesn't use some piece of imported trash to teach on, and I have to attack pop music by listening to the tracks note by note and writing them out on note paper, before I pick up a pop song. (Or play one of those dippy, incorrect arrangements they sell at the music store).
However slow the first year or two will be, find a teacher and take a course of lessons. I'm not sure one needs a lesson a week over 8 years as I had, but certainly checking in occasionally to have bad habits detected is extremely useful. One can now, compare ones performance on many standard pieces, to the performances on record, CD, or even the internet. This reference check to recordings was not available when I was a student, or actually cost more than piano lessons until recently. Piano lessons were local and $10 for 1/2 hour, a LP of a piece was $6 and took three hours on the bus to get downtown and back, if the record department even had the piece one was learning to play, before the internet.
So, be bold, go out and find a teacher, however peripheral the experience will be to playing the pop pieces you want to play. A comes before B in my opinion, and those of my friends who were self taught, I find a bit rudimentary with the occasional glaring error that I have to keep my mouth shut about. One of these self taught tyros runs the music program now at my church, and I have as a result, given up singing with the congregation. She is so "filled with the spirit" she can't play the song through on consecutive verses with the same backup chord structure, which leaves everybody out except the sopranos that can sing the melody. But, I have to say, she is very popular.
You do have the advantage, you have an adult approach to the hobby and will probably spend the time to practice effectively now. It is a pity you didn't develop the passion to create music yourself back when time laid heavy on the hands, but one doesn't often buy into idea that your parents thought up. I had the advantage in the fifties, the alternatives to piano were softball in the street, at which I was awful, and three channels of network television, which were as bad as visits to the dentist, IMHO.
Topic: Dropped Piano years ago, how to start again?