There are more and more camo patterns out there which match up for dry grasses. Kuiu Vias and Under Armour RR Barren are two I use. Mil-surp desert camo will work fine, as will any sand/tan solid shirt as well. Even ACU digital does better than a guy would think.
Once your color tones match up fairly well, shoot from seated or prone, and use landforms to your advantage. Even in flat land, there's a lot more "person sized" terrain forms than a guy might expect. It's a bit of a compromise, since you lose visibility of the field by sinking yourself into the scrub and terrain, but you also hide your form. With a low seat and a back rest (natural or equipped), shooting nearly supine, a guy can keep a decent field view without offering a high body profile.
For me, it's really about reading the travel patterns and anticipating the approach. A guy might be fully exposed from one approach angle, but effectively invisible from another. Being able to read terrain forms through binos is a critical aspect of this, for me.