
Fairly frequently articles come up outlining how important it is to buy certain foods organic while other foods are less dangerous in their "traditional" form. Find a list you trust, memorize a few key foods that you often buy, and get shopping!
Here's the information from one such article:
Should Buy Organic
-Milk
-Meats
FRUITS:
-Peaches
-Apples
-Nectarines
-Strawberries
-Cherries
-Grapes
-Pears
-Raspberries
-Plums
-Oranges
-Tangerine
-Cantaloupe
-Lemon
-Honeydew
-Grapefruit
-Watermelon
-Blueberries
VEGETABLES:
-Sweet Bell Peppers
-Celery
-Lettuce
-Spinach
-Potatoes
-Carrots
-Green Beans
-Hot Peppers
-Cucumbers
-Cauliflower
-Mushrooms
-Winter Squash
-Tomatoes
-Sweet Potatoes
Don't Have to Buy Organic
-Avocado
-Banana
-Pineapple
-Kiwi
-Mango
-Papaya
-Asparagus
-Broccoli
-Cabbage
-Onions
Image from http://tbn2.google.com/images?q=tbn:RIA2pRwDp4HIpM:http://whatscookingamerica.net/Fruit/AvocadoPhoto.jpg