Most houseplant trouble comes down to a small number of fundamentals: light, water, and patience. Getting these right solves the majority of problems before they start.
Light is usually the first thing to check. A plant that is struggling is more often under-lit than over-watered, so before adjusting your watering schedule, consider whether it is getting the light its species actually needs.
When it comes to watering, checking the soil before reaching for the watering can is more reliable than sticking to a fixed schedule. Most common houseplants prefer to dry out somewhat between waterings rather than staying constantly damp.
Lastly, give new plants time to adjust to their environment before assuming something is wrong. A little patience, paired with consistent light and watering habits, is usually all that is needed.