I never took piano lessons ... but then again I'm not exactly a "classical" player**. I do use a fairly proper fingering technique that I've modified over the years as I developed my style.
Get the Czerny and Hanon (
http://www.danmansmusic.com/free_hanon.htm) exercise books. They will help build dexterity and muscle memory. However, if all you want to do is be able to play popular (as opposed to classical) music then you probably won't need them.
Not to belabor the point with regard to an instructor, you might want to get a couple of "consultations" rather than full on lessons; most grad students will do that.
Will is partly right when it comes to damaging your hands with improper technique. However, life-long classical pianists almost certainly damage their hands regardless of proper technique--I have a couple of older pianist friends who have problems. One of them has had to have her hands operated on (she's in her late 60's); and she has a PhD in Music and a Masters in Piano (she was a Beethoven fanatic, which is probably what ruined her hands). Our hands were NOT designed to play piano and any kind of repetitive motion that is unnatural MAY result in damage. So unless you're planning on doing this for a living for the next 60 years you probably don't need to worry about it.
**I did take classical violin lessons.