learning to dance  

I'm thinking on learning dance (jazz and ballet specifically), but because of my age (I'm 19 actually without zero dance background), I suppose I am considered a very very late starter. But learning the basic foundations and techniques is something which I have always wanted to do, so I would really like to try it out.

I understand that dancers do quite a lot of flexbility and muscle conditioning training, so is there anything that I should take note of before going for my first lesson (for e.g. how I should be physically prepared)?

Besides, is it appropriate to start with ballet and jazz?