There is no single way to be sustainable, and very often you will find that environmentally conscious people will propose radically different solutions. There is always the option to buy shiny solar panels, wind turbines, or you could always completely overhaul your house. These are all solutions that would bring about great environmental benefits, however they can be capital extensive.
Do not despair if you cannot afford these high tech solutions, this is no time to be a pessimist. So do not give up, there are thousands of ways you can reduce your impact. Some solutions that can be made to your household can be found in one of my past blogs here Ways to Improve the Efficiency of your Home. There are great low tech solutions available that do not require excessive amounts of effort or cash.
Most of us take showers, and we all know that the water temperature is not immediately desirable. As we can not afford a grey water system, we will most often let the water flow down the drain. You can change this by taking an empty container, bucket etc. and placing it under the shower head until the desired temperature is achieved. You can then place the bucket down an quickly jump into the shower. The water that you collected can be used to do anything, you could use it to cook, water your plants, or you can dump it into the toilet bowl when it needs to be flushed, or into the toilet tank after the flush.
You could also buy a shut off valve to install on your shower head piping. The navy being stranded in the middle of a salt water ocean, have to really make an effort to conserve water. The navy utilize a method of showering called a "navy shower." Your shower essentially consists of getting yourself wet, and then closing the shut off valve. You would then lather yourself up with soaps before you turn the water on again. This form of showering only uses the bare minimum and you would only use 6L of water.
Another inexpensive way you can reduce your impact, is to repurpose and reuse furniture, clothing, or anything else. Instead of giving up on the item and throwing it into the trash, take a second to brainstorm other ways it can be used. Can it be fixed up to serve its original purpose? Is there a way to spruce it up and give it the appeal that it once had? If it cannot be salvaged to serve its intended purpose, try to put it to use in a way you never thought of. Turn an old door into a new table, turn an old table into shelves, cut old t-shirts into rags.
If you cannot think of a way to repurpose do not throw it into the recycling right away, especially if it is particularly large. Phone up your local charities and see if they will take it off your hands. Take a picture of it and place a free ad on Kijiji.
Our consumerist society does not inspire creativity any more, sure it is easy to chuck the product in the trash knowing that you can buy a new one by walking into your local store. Your old product required energy in order to manufacture, as does any new replacement. You should try and prolong its lifetime as much as possible to reduce its impact.