well, i did try... i remember going into a place that looked like a restaurant, and i smiled said i wanted to eat, i made the international "eat" gesture w/putting my hand to my mouth. and the guy said, "No." i was so embarrassed, i left and didnt go anywhere by myself to eat for months. maybe he thought i was a beggar, maybe he didnt want to deal w/someone who didnt speak korean, maybe he hated my glasses, who knows...
look for convenience stores. Places like Family Mart, Buy The Way, or GS Mart. 7-11 is here as well. it's cheaper of course to buy at a proper grocery store (big bottles of water are around 2-3,000 won {$2-3}, but you can buy a whole pack of 6 for under $5 at emart). BUT if youre fresh off the plane like i was, you just want something to eat and drink.
ramen is easiest and cheapest. a big ol' cup of ramen is under one dollar (around 750-900 won). at the store, they have hot water dispensers and chopsticks gratis, sometimes you'll see students standing at a little table slurping down their noodles before their next hogwan. spaghetti ramen is my favorite. ramen bokki is good too, but a tad spicy. most of the ramens are spicy. if youre a baby about spicy/hot like i am, buy a milk or yogurt or something dairy to go along with your food to sooth the palette.
also good to try are these little triangles. they're seaweed with rice inside and some sort of filling. i cant read korean and it's a gamble when i buy them as to what i'm getting, but ive never had one that i didnt like. i always hope for the tuna. they are also under a dollar, maybe 900 won or so.
there's fruit and veggies to buy too, but if it's the right season, you can walk around and see a truck parked w/a guy selling fruit. the tangerines this year were fucking awesome. the apples are bomb, and some other fruit that tastes like a sweet pear, but it's round. i thought it was a vegetable. take a gamble and buy an assortment of things, it's fun, es un adventura, si mon.
my hotel had a hot/cold water dispenser, so i bought ramen en mass and kept them in my room... b/c again, i am from southern cali and the cold here made me never leave my room unless i absolutely had to.
also look for a "fast food" chain called Hansot. they're little lunch counters, they have pictures on the menu and you can just point to what you want, it's wonderful. food there runs from $1.50 to $6.00, most meals i spent around three. you get a tray of rice and whatevers. as i was so sick of ramen when i found hansot, it was the most delicious food i'd ever eaten in my life.