1. Bring Your Own Bag: The EPA reports that between 500 billion and 1 trillion plastic bags are used each year worldwide. Avoid this needless waste by always carrying a bag or two with you and be sure to bring grocery bags and produce bags with you when you go to the market. Ecobags offers a wide variety of cotton and string bags that a great for grocery shopping, and you can also probably find great canvas bags at your local thrift shop. See here for tips on how to remember your grocery bags when you go shopping.
2. Drink Tap Water: Americans consume at least 22 billion bottles of water each year (I've also seen statistics reporting much greater numbers), and nearly all of these plastic bottles end up in the landfill. Unless you have serious water quality or taste issues, this is an easy way to curb usage. Here's an additional list of reasons not to drink bottled water.
3. Buy from Bulk Bins: This is a great way to avoid buying food products in plastic packaging. Stores like Whole Foods offer granola, cereal, dried fruit, dried beans, nuts, candy, and grains that you can bring home with reusable cloth bags. Use the internet to find out if you have stores in your area with bulk bins.
4. Carry a Reusable Water Bottle: Sometimes you just need a drink, so be sure to carry a reusable water bottle with you. Don't forget that Nalgene bottles are made of polycarbonate, a type of plastic that is likely to have many adverse health effects.
5. Bring Your Own Mug: If you love hot beverages, be sure to carry along a mug. Stainless steel mugs are a great option.
6. Discover Fresh Foods: Almost all processed foods come in plastic in some form or another. Buy fresh fruits and veggies (be sure to use your produce bags!), get your meat wrapped in paper from the meat counter, and find a deli where you can get your cheese in paper.