I'm a first year graduate student, and last semester was my first exposure to real fluid mechanics (i.e., beyond the basics of pressure, volume, temperature that you study in thermodynamics with regards to equilibrium ideal gasses). Basically this was a treatment of the Navier-Stokes equation (both viscous and inviscid) and the Boussinesq approximation. The class was first year graduate Mechanics, and it was taught out of Fetter and Walecka's Theoretical Mechanics of Particles and Continua. I would NOT recommend this book if you want to teach yourself--it's super tough to read and the problems are very challenging.
Before getting to fluid mechanics in class, though, we had to pick a topic for a final project. The topic I (stupidly) picked was deriving and simulating the equations of two-dimensional fluid flow in a plane subject to a coriolis force--i.e. the "beta plane approximation" you find in meteorology. So my research would be classified as "Geophysical fluid dynamics."
I was pretty much completely ignorant to fluid mechanics going into this, and we only really spent the last two weeks of class on fluid dynamics, so I was basically forced to learn as much fluid dynamics as quickly as I could to do this project (I had about a month). After struggling too much with Fetter and Walecka, I opened up the absolute best introduction I've seen to fluid mechanics:
Feynman Lectures on Physics, Volume 2, Chapters 40 and 41, respectively called "The Flow of Dry Water" and "The Flow of Wet Water" (referring to inviscid and viscous fluids.)
Strongly recommended as an introduction for anyone interested in any kind of fluid mechanics.
My research was on geophysical fluid dynamics, so I didn't look through all the fluid dynamics textbooks out there, but the only other book that I found readable and useful for learning was Benoit Roisin's relatively new book
Introduction to Geophysical Fluid Dynamics: Physical and Numerical Aspects.
I found that nearly all the other fluid dynamics textbooks were just too stuffy and intended more as reference books rather than learning/teaching books. The treatments of fluid dynamics you find in most mechanics books are also usually extremely terse and not very good for learning. For example, Fetter and Walecka's treatment is very theoretical and basically saturates the lower bound on the amount of intuitive explanation needed to connect all the equations. Another example is Pedlosky's Geophysical Fluid Dynamics, which seems intended as a reference book for meteorologists rather than physicists, since he tries his hardest express all the equations in latitude-longitude-altitude coordinates even in things like plane approximations.
Then again, all of these might be too advanced for you. Fluid mechanics is an intrinsically difficult subject and the best way to be introduced to it is by first understanding the mechanics of particles really well, especially nonlinear mechanics, then studying all the continuum-limits including strings and membranes, and only THEN going into fluids.