Lets keep things super simple.
How often should I water my plants? The answer is, when they need water. Most plants need watering when the top 2-3cm of the soil is completely dry. Use your finger to test the moisture level of the soil. This could equate to every 3 days or every 2 weeks! Keep it simple, stick to the finger test.
How should I water my plants? Soak the soil with water. In a shower, using a hose, a tap, a watering can, etc. Thoroughly soak until water is flowing from the pots bottom drainage holes. Let your plant drain all of the excess water before putting back inside a decorative pot.
What is overwatering? By overwatering we really mean frequency of watering and not the volume. Overwatering is watering your plant when the soil is still wet. Allow the top 2-3cm (at least) of the soil to dry completely before watering.
Can I use Tap water? Yes! Tap is fine. It can cause minor imperfections with mineral buildup in plants leaves. If you're looking for better, use rainwater or distilled.
How much light does my plant need? Some natural light. Every plants lighting requirements is different. To keep it super simple, within 2 metres of a window is a good starting point. Get the watering right, keep your plant in the same spot and monitor it. If your plants leaves are changing colour, or its looking a little bit leggy. It most likely needs some more rays.