I found Halo "Premium Grade Screen Protectors" for the S5 the other day and ordered them. I just put one on following the method here. I have never put on a screen protector before this one (the salesman at the store put the one on my old phone) but have to say that it was fairly easy. Overall, for the price paid, I can say that these are pretty nice screen protectors.
Attached are before and after shots as well as pictures of the product.