I reuse bags as much as I can. I used to buy pre-made frozen bird food for my pet birds. The bags it came in were so heavy-duty I started buying the ingredients instead and making the bird food myself. I also reuse other bags that stuff comes in as much as possible. Recently I learned that you can fuse plastic bags together with an iron and sew the pieces together to make things. I use a cloth bag for grocery shopping, but as I walk to work I find plastic bags in the street every day. I'm going to sew a backpack out of plastic bags and be the envy of all my environmentalist hiking buddies.
I also reuse plastic bottles. Instead of Nalgenes I use Gatorade or similar bottles. I've got a Naked Juice bottle I was given for free in Stehekin Washington while I was hiking the Pacific Crest Trail. I drank the stuff inside and still use the bottle. I also found a nice 1-liter bottle on the trail. I washed it and used it on my trip and still have it. I rarely buy plastic drink bottles myself since I don't like caffeine or corn syrup.
I'm going to start carrying a set of eating utensils with me and I already bring a cup if I'm going somewhere for coffee. A lady came on one of my Sierra Club hikes with her sandwich wrapped in an air-tight, reusable wrapper. It was some kind of red-checked cloth coated in plastic. I might try to make something similar, minus the coating. I might make some cloth produce bags, too, for the farmer's market and bulk foods at the grocery.
As a backpacker I have been wondering if perhaps a woven reed mat would work as well as a foam pad. I've been thinking about weaving one myself out of cattails or tule someday. It might be too heavy, but it wouldn't hurt to try. I once took a basketry class. I might be able to figure it out.
But I'm only one person in a sea of 6 billion people. The amount of plastic everywhere in Mumbai alone -- knee deep in many places -- is very depressing. I wish more people cared and not just sensitive white American bird-lovers like myself.