The secret to a cheap and fast make over is really very simple.

THROW OUT
What you need and what is in excess. Throw out what you have not used for the past six months - chances are you won't even miss it. This will free up space that was previously occupied by things not used. You will be amazed at how much space you suddenly have!
GARAGE SALE
If what you have are still fairly new, have a garage sale and get some extra cash. What cannot be sold, please don't bring it back into the house! Give it away to charity or other needy family that could do with it more than you do.

REARRANGE
Once you have created the extra space, you can start moving furniture around the house. But before you move the heavy furniture around, take out a measuring tape and do some measurements in where you would like the piece to be. No sense hauling the furniture to the new area to find that your cupboard sticks out and blocks the door way!
PAINT
Walls, that are peeling or discoloured, with a fresh coat of paint makes the whole place look brand new. If you have friends who are artistic, get them to paint a mural on your wall. If not, there are lots of DIY stores where they sell stencils, you will have a great time selecting the theme.
TAKE YOUR TIME
Something done well takes time, but don't drag your feet! The daily routine still has to run, so try to do this during the school break if you have children and get them involved as well, especially when it comes to their room.

ROOM BY ROOM
If you intend to do the whole house, work it through systematically. Otherwise, everything will get lost in the pile. As you clear one room, give it a thorough cleaning at the same time - after all, the furniture has already been moved!
Simple, fast and cheap. You need your friends and family's help if you want it done faster (though sometimes, they will hinder you more!) and you might even get better ideas from them. If you are not pleased with the final result, you can always do it all over again!
Have a great time in your new space!