Start with 'On Basilisk Station' Wolf, which is book 1 of the series. And David Weber is a bit of a military history buff (cough), so you'll find that if you know naval history, the flow of some of the battles seem familiar.

Just be aware: It's already known that things will be changed. In the books, physics are consistent with the propulsion and ftl systems, so basically -all- military ships resemble a spindle with tapered ends (differences being in the shape of the fore and aft hammerheads where the alpha and beta nodes are, the placement of point defense, missle tubes, grasers, etc). The movie makers have already said they are changing that so the average movie goer can tell one star nations vessels from another. Just like they decided to start with book 2, with Honor a captain and dealing with less of the way she got there (ie: the stuff that led to her being senior officer on Basilisk Station. Nuff said, no spoilers).

But Weber is consistent with his world and the way it works. Things evolve over time, not change by authorial fiat. And oh, is the ride worth the ticket, IMHO.