Once you have procured some good tools and prepared your soil (don't forget to add compost), you are ready to consider deeply how to apply water to your garden. While many common landscape plants have shallow, spreading root systems, most of our garden vegetables are tap-rooted. Hence, the standard landscape irrigation system which provides frequent, shallow waterings will not properly satisfy your garden crops. In the heat of the summer, surface soil temperatures can rise over 100 degrees and if your tomatoes or lettuces have not established deep roots in moist soils, they will wilt dramatically. You might see this and rush out panicking to blast them with a jet of water from the garden hose. They survive, but the leaves on the lettuce are bitter and the tomatoes don't produce well.
We encourage you to water your garden more deeply and less frequently. This involves investing in some irrigation devices. Look for some kind of drip irrigation that provides a slow, continuous seep that does not form puddles on the surface of the soil. One good choice for a long-lasting system is a 1/4" or 1/2" Emitter Line. The flow rate is about 1/2gal/hr per emitter with 6" or 12" spacing between emitters. They work best at about 10-20 psi so you will need a pressure regulator for the hose end. The line is connected with 'T's and 1/2" poly tubing to your hose bib.
If your plants are in the ground and the soil is sandy, expect to water once or twice a week for 1-2 hours at a time. In a 4'x8' planting bed with emitters every 6" you will run about 24' of tubing, so 2 hours of watering uses 25 gallons - a little more than the average shower. In heavier clay soils that hold moisture you may want to water more deeply and less often.
If you are gardening in raised beds or large pots, your plants will need more frequent watering. This will depend on the type of soil mix that you are using, the sun exposure and the size of the containers. If plants are looking like they need water every day, then they are either not getting deep enough water, the soil structure is poor, or the pot is too small. Always wait until the surface of the soil is dry before watering as many plants are sensitive about soggy conditions.
Keep in mind that correct watering is one of the most important aspects of good gardening and it is both a skill and an art. Pay close attention to your plants and experiment with different systems, durations and timings. Try to imagine what is going on deep beneath the surface of the ground where the plants are rooting down.
One local source for finding the pieces and parts for a drip irrigation system is All Around Landscape Supply - they have a store in Carpenteria, Santa Barbara, and Santa Ynez.