I am an omnivore. I eat a low-meat diet (~200 g/week) because of health and environmental concerns. In an average week, I cook vegetarian food five times, fowl one night, and red meat once.
In general, I prefer naturally meat-free vegetarian dishes, although I do make use of some meat substitutes.
I aim for local and seasonal produce, but find this difficult because my local market doesn't label produce, and I'm a city dweller--which means I have a tiny kitchen with little storage space, rely on public transport or my feet to get ingredients home (local farmers aren't within my transport range), and don't have a garden.
I shop for produce about once a week at the open air market, and my decision of what to cook is largely determined by which vegetables will spoil first.