Small homes are not short of space so much as short of usable space. There is almost always room above head height, behind doors and under furniture that is doing nothing, and filling it well is what makes the difference between cramped and compact.
Use the top two feet
Most rooms have a band between the top of the furniture and the ceiling that is completely empty. A shelf up there takes books, boxes and anything used rarely, and because it is above eye level it does not make the room feel smaller in the way a tall unit in the middle of a wall does. Fix it properly into the structure rather than into plasterboard alone if it is carrying weight.
The back of every door
Door backs are the most wasted surface in a flat. Over-door hooks and shallow racks take coats, bags, cleaning cloths, shoes and the ironing board. Keep it shallow, because anything that fouls the door frame will be taken down within a week.
Make furniture do two jobs
In a small room every item should either store something or be essential. A bed with drawers under it holds a season of clothes. A storage ottoman takes bedding and gives you a seat. A hollow footstool swallows the things that otherwise live on the floor. This is the one area where buying something genuinely solves the problem rather than relocating it, though it only works if you measure first, because furniture that nearly fits is worse than none.
Under the bed, but contained
Loose items under a bed collect dust and become unreachable. Shallow boxes on castors, pulled out in one movement, turn the same space into real storage. Measure the clearance before buying, including any central support rail, which is the thing that catches people out.
Vertical in the awkward gaps
The space beside a fridge, behind a bathroom door or at the end of a hall is often four or five inches wide and treated as unusable. Narrow full-height units fit exactly there and hold a surprising amount, because depth matters far less than people expect for tins, bottles and toiletries.
Keep the floor clear
A small room reads as cluttered mainly from the floor up. Wall-mounting what can be wall-mounted, including shelves, hooks and where possible a bedside surface, does more for how a room feels than any amount of rearranging. It also makes cleaning quick, which matters more in a small space because there is nowhere for dust to be out of sight.
The limit worth accepting
There is a point at which a small home is simply full, and no further organisation will help. Recognising it saves a lot of wasted effort and money on clever storage that cannot change the arithmetic. At that point the only real options are fewer possessions or more space, and it is worth saying plainly rather than buying another set of boxes.