Awkward corners can be converted into storage space. Light coloured cupboards, maybe the same colour of the walls, will blend in well, give you more space to store knick-knacks and get rid of awkward corners for you.
Use wall space above six feet to construct more storage space. Again, if coloured the same colour as the walls, the room will look less restricted.
Have hooks put up in your ceiling. You can hang potted plants and other decorations from there. It will save space, yet, make your house look nice.
Add hooks under shelves as well. You can hang mugs, keys, etc here. If the mugs are nice and colourful, they will look like accessories too.
Install sofa cum beds. They are comfortable, useful and occupy less space when they are folded up.
Large windows or skylights give the illusion of more space. They certainly let in a lot of light and air into the house.
The empty suitcases you have in your attic, garage or under your bed are ideal for packing in seasonal clothing, your book collection or even old files. Large suitcases are like extra closets.
Cupboards can be built in the area under the staircase. They are ideal to use as storage space.
Give away all that you don`t use regularly. Look at any item you have stored away. If you use anything less than once a year, maybe it is time to give it away. It`s just occupying unnecessary space.