The first tip to reducing household waste is to buy less stuff (especially stuff of the plastic kind), and to buy more carefully. We live a life of luxury and abundance (even if it doesn't always seem that way), are tempted by the many bargains and sales that pressure us into buying, and often make spontaneous purchases that we don't need or even like (hence buyer's remorse). With regard to quality over quantity my dad used to say that he "can't afford to buy cheap." What he meant was that cheap stuff breaks faster and therefore needs to be replaced faster, and so ultimately costs more (and creates more waste). Better to buy good quality items even if they are more expensive upfront. They will last longer and are a better investment in the long run.
Next tip is to recycle and buy recycled, aka second hand. This also reduces the amount of things that need to be manufactured, and the amount of things going into the waste stream. I buy a lot of clothes at second hand shops (I find more interesting things there, and I do hate mall shopping with a passion), donate unwanted furnishing items to a local shelter coordinator, and unwanted books to my local library. You can also resell your books on cash4books.net, as a friend recently pointed out. There are second hand shops for furniture now, and then there are whole organizations, such as Freecycle.org, that do nothing but help people shuffle their unwanted stuff around. Check it out, they have local chapters everywhere.
Repair, repair, repair is my mantra. Recently, I had a pair of 20-year-old leather boots repaired that was still in good condition and which I really like. The repair was not inexpensive, but I prevented the boots from filling the landfill some more and I supported my local cobbler. Unfortunately, many appliances and electronics are inexpensive and have what they call "built-in obsolescence," and are often impossible to get repaired. It is frustrating. But I spent a few hundred dollars more on a new washing machine recently, which is supposed to last 15-20 years, instead of another one I was considering with an 8-10 year lifespan.
And lastly, I use www.ourcommonplace.com/yourlocation quite frequently for either donating and selling items, or requesting things I need. A while ago I needed reusable name tag holders for a local non-profit and found them for free from someone who had a box of them stashed away they no longer needed. More recently, we were looking for a ping pong table and I asked the local commonplace forum whether anyone was selling a used ping pong table. Lo and behold, a kind neighbor offered us one for free.