I like most of John Ringo's stuff. But some people hate it. And some people just say "
Oh, John Ringo, No!"
If you've never read any of his stuff before, perhaps
A Hymn Before Battle is as good a place to start as any. Classic Mil SF. It's free, too.
Or if you'd like a shorter series, start with
March Upcountry, the first of four books. Mill SF including a coming-of-age story. It's also free.
If fantasy is more your thing,
Princess of Wands is good, and the long-awaited sequel, Queen of Wands should be out August.
But unless you're really into BDSM erotica and hero fantasies,
don't start with
Ghost! (Which is the book that started the "Oh, John Ringo, No!" meme.)