The best reason to choose a landscape is often the simplest: it makes you stop. That may be the glow behind a ridge, a pocket of quiet between dark trees, the motion in a painted sky, or a color you can't quite leave alone. Let that first response lead. Landscape paintings do not need to match every detail of a room to belong there. They can give one wall a view, a rhythm, or a moment of breathing space.
Once a few works stand out, consider where you will see them most often. Small paintings are especially good near the places where your attention naturally slows down: a reading chair, a writing desk, a bedside wall, an entry, or the turn of a hallway. Taping out the finished dimensions is a practical way to understand the scale before a piece arrives, especially when it includes a mat or frame.
Think about the light in that part of the room, too. A watercolor can feel especially soft near daylight, while an oil painting may show more of its surface under a nearby lamp. A warm field can brighten a quieter wall. A darker ridge or coastal scene can give a bright room a deeper note. There is no fixed rule. The right painting is the one you want to meet in that place again and again.
If you are choosing between oil and watercolor, begin with the quality of attention you want the work to carry. Watercolor often lets the paper and transparent layers keep the scene light and atmospheric. Oil can bring a denser surface, stronger texture, and a more physical sense of color. Neither is a better choice in general. A misty watercolor may be exactly right for one room, while a small oil with a brighter edge of paint may be the view that gives another room its needed focus.
A compact landscape also makes collecting feel possible without rushing it. One scene can stand alone, or you can slowly gather a group connected by mood, light, place, or medium. A watercolor and an oil can sit well together when they share the same sense of attention. The collection does not have to be finished to feel personal. It can grow whenever another view starts to feel like yours.