Just because you need a table and can get it through the front door, that doesn't mean it's right for the space. Put another way, if you can't walk around the furniture or it looks cluttered, either there's too much stuff or the stuff is too big.
Some things are easy fixes, like taking all the expanding leaves out of tables to make it as small as possible. Others can be more challenging, like fitting a big bed into a small bedroom. The bad news is that if it looks too big, it probably is. The good news is that you might be able to fix it.
Your bed is probably the largest piece of furniture you own. Short of getting a Murphy bed that folds into a cabinet or wall, the best way to integrate the bed into the surrounding room is to have it blend in with the walls and carpet. If you don't have room for bedside tables after the bed is in place, try putting floating shelves on the walls. You'll be saving space and giving yourself an area for a lamp and alarm clock.
Couches come in a variety of sizes, but in very small areas, a loveseat might do just as well. You can always keep a couple of folding chairs in a closet if you need them. Go for glass-topped tables; they improve the visual proportions of the space without sacrificing function.
Try for chairs with exposed, narrower legs and sofas without pleated skirts. Embrace lighter wood finishes to make tables look smaller, and use lamps with light shades and narrower profiles. Light is good, and decorating with lamps as accent pieces is a way to create multiple warm pools of light that make a small space look larger and more inviting.
Too many accessories make small spaces look cluttered, and when they're too large, they look clunky and mismatched. The best solution is to audition accessories and place them in groups of two or three items throughout your space. Leave plenty of open, uncluttered area around them.
In the next section, we'll look at why a straight line between two points may not be the best design solution.