I am no expert in this area, but have significantly reduced the consumption of water in our household from 1,400 litres / day to 400 litres / day.  

We are located in Brisbane, Australia and have a large brick veneer single storey house on a concrete slab in the Western Suburbs.

To save water we have implemented the following changes:

1. Turning off the sprinkler system and instead watering by hand.  This has been forced on us due to level 2 water restrictions being put in place in Brisbane Australia.
2. Fitting low flow (AAA water rated) shower roses to both showers in the house. This had a significant affect to water consumption and had little effect on our quality of life (provided you choose a good one).
3. Cutting our water downpipes (3 of) that did discharge off the roof onto the street to make them discharge onto the lawn.  This reduced the need to water the front lawn particularly after rain.
4. Upgrade of our washing machine after the old one wore out to a front loader.  This uses 80 l/wash instead of 200 l/wash (as saving of 120 l/day)
5. Capture of one downpipe for storm water from the roof into the backyard pool. This has reduced the need to top up the pool.
6. Turning down the main supply tap to reduce water pressure.  This works a treat and costs nothing.  Simply reduce the amount of water available at any one time and you automatically save water. Balance this with inconvenience to be fair.  An even better solution would be a pressure reduction valve but this costs money.
7. When updating our bathroom, we chose 6/9 dual flush low use water toilets.  The en-suite bathroom which did not need updating we lowered the flush level and placed bottles (milk bottles) to reduce the amount of water used at each flush.  Some people use bricks but this can lead to particles blocking the flush mechanism.
8. Placement of buckets at both the kitchen sink and bathroom sinks.  This has reduced the need to run fresh water for simple tasks such as washing hands, washing fruit or cleaning scraps from dirty plates. Although fresh water is used for final cleaning it reduces the need to use fresh water for all.  It has the added advantage of being able to carry it outside to water pot plants and gardens if time avails.
9. Grey water reuse.  Although currently not legal in some Council areas:
1.  grey water from the kitchen sink has been diverted to the front lawn.  This has been attached to a drainage hose to disperse this over a wide area.
2. Washing machine.  Here a grey water kit has been used as it has been difficult to obtain the grey water as we have a slab house and access to the drain is only 300m above ground level.  A new hole was made through the brick wall and a similar size pipe to the washing machine outlet attached.  This enables the washing machine drain pump to be utilised to push water higher.  In our case into a wheel barrow for usage on the gardens and lawn.

Options being considered in the future:

1. Installation of rainwater tanks to feed the toilet water supply possibly fed by the washing machine waste water (but apparently you have to use this within 24 hours to stop contamination). 
2. Installation of another rainwater tank for the garden.