Rituals
A Puja Corner in a Rented Flat
No dedicated room, no drilling, no conversation with the landlord.
Most homes do not have a puja room, and a rented flat rules out half the usual advice. It matters less than people think.
Pick the direction first
North-east if the flat allows it, facing east when you sit. If the layout makes that impossible, a clean and quiet corner you will actually use beats a correct one you avoid.
Nothing that needs a wall
A wooden chowki, a shelf that stands on its own, or the top of a low cupboard cleared for the purpose. A folding chowki can be put away entirely, which matters in a shared flat.
Keep the floor clear
Oil and ash will find the floor. A brass or steel tray under the lamp catches both and wipes clean, and it saves an argument about the deposit.
Light and air
Somewhere with a window if you can. Camphor and agarbatti need the air to move, and a closed corner holds the smoke longer than is pleasant.
Small is fine
A lamp, a picture, a small tray, a place to sit. Everything else is addition rather than requirement.