By not pampering your plants too much with water you can save a lot of water.
If you water your plant it will prevent them from growing their roots deep into the ground. There is no need for them if the water can be obtained near the surface. That means that these plants will dry out sooner in dry spells without receiving extra water.
The newly planted plants do not have so many and not such deep rooted roots. Those plants do need extra attention and extra water. Keep the watering to a minimum so that you encourage them to shoot their root deeper into the ground so that they can manage on their own. In exceptionally dry periods you might have to aid a little but that will not be as often and not for all plants. You will see soon enough if a plants really needs water. Some of the plants get flabby leaves in the burning sun but as soon as the sun is gone they will rise again. That does not necessarily mean that they need water. You will learn to know your plants soon enough to know if they really need water or not. If you hold back on the watering you will notice that you do not have to use so much water any more even in dry periods.
Put the plants in the right place
In order to use little water it helps if you put the plants in the right place. If you know that a plant wants a lot of moist it is wise to place it in a spot that is naturally more moist. I have replanted some of my plants because the spot I had chosen was too dry. Last year I have even sold my garden hose because I no longer need it. For some plants in a dry period I use a watering can but that is not very often. That is the way to enjoy your garden to the max and save water.
By place your plants in the right spot you also make it less susceptible for diseases. So if you see that a plant does not do so well in one spot replant it somewhere else.