You can tell quickly if your plants need water by digging around with your hands, a soil probe, garden trowel, or shovel. Don’t wait for the plants to tell you by wilting and leaves dropping off! Pull the mulch back, stick your finger in the ground and see if it is wet or dry. Avoid watering so much that there is standing water. This could cause the plants to develop other issues.
Utilize tools that are in most box stores or even laying around in your garage. Watering wands (similar to a shower head), you can attach it to the end of your hose and water each plant individually for about 15-20 seconds, take a 20 second break, then come back and repeat for another 15-20 seconds for that small plant. For larger areas of annuals or ground cover, you may want to consider using an overhead sprinkler.
Try to avoid watering in the evening hours or 3-4 hours from dusk. The best time to water is in the morning. This helps prevent the plants from remaining wet all night and fungus/disease developing.