A typical view of a Saltmarsh Sparrow is a little dot teed up on a clump of grass far out in the marsh. Their song is very quiet and is often extremely difficult to hear. The sparrows feed mouselike, creeping around in the grass and pop up every now and then for a view of their territory. The best look you can get at one is often acquired by sitting in a place where you have seen one, often at the edges of small muddy pools or channels, and waiting. As far as I've found out this is also the best way to photograph them.
This is one of those birds that if you're not actively looking for you will probably never see it. Even when they are perched up and in view, they are very unobtrusively colored and can be practically invisible in a wide open area. Up close however, I find them quite striking and unique.