To lower your footprint it is best to eat less often and less quantities of meat. Also you can pay attention to what kind of meat you eat: Chicken has the lowest footprint of the most consumed kinds of meat. Pork is again lower than beef. Please note: if you choose a meat substitute with cheese in it, it might have a footprint as higher than pork. There are also fishes that have a higher foot print, such as most bottom fishes (if caught by trawling).
Alternatives for meat -in the sense that they contain an equal amount of vitamins and proteins- :