There are a few kinds of habitat (see below). Study up on eBird on what has been seen and you may want to pick an area to focus on. It's a really big site. For instance, if you are interested in grass birds you may want to hike into the big wildflower prairie area and focus there. 

Henslow's Sparrows, Dicksissel, Indigo Bunting, Red Headed Woodpeckers, all kinds of water fowl.

There is a small parking lot at the north east corner. This is a big space--a large flower covered meadow area, good for spotting sparrows, edged by trees, with some snags. A large pond in the middle that attracts water birds, and another large meadow on the other side. The wooded areas attract a lot of song birds--Indigo Bunting for example. There's a lot to see!