Every room has a light budget, and every plant has a minimum. Before you buy a new plant, spend a day noticing where direct sun falls, where bright indirect light fills the space, and where the room settles into comfortable shade. A south-facing window in the northern hemisphere is your brightest asset; a north-facing one gives you the gentlest, most consistent indirect light.
Bright indirect light is the sweet spot for most popular houseplants. It means a plant can see open sky from its position but is shielded from the harsh beam of direct afternoon sun. A metre or two back from a south or west window, or right on the sill of a north or east window, usually delivers this. Sheer curtains diffuse summer sun beautifully without plunging the room into shade.
Direct sun is not the enemy, but it is selective. Succulents, cacti, and some hoyas actively want several hours of direct rays each day. The risk with thin-leaved tropical plants in direct sun is leaf scorch, which shows up as bleached, papery patches. If you notice this, move the plant further from the glass or add a filter.
Low light does not mean no light. It means a plant receives no direct sun and sits far enough from a window that your eye takes a moment to adjust when you walk in. Very few houseplants truly thrive in these conditions, but cast iron plant, ZZ plant, and some pothos varieties tolerate them well. Manage your expectations: growth will be slow, and watering intervals will stretch out considerably.
Rotate your plants a quarter turn every time you water. This simple habit keeps growth even and prevents one side reaching toward the light while the other sits in shadow. It also gives you a regular opportunity to inspect leaves up close and catch pests or problems early.