How can I make a flat homely?

I don't want to put posters, paintings or photographs up on the walls because this is a housing association property and they want tenants to fill in holes and plaster and paint before moving out again.

I have no DIY skills and haven't got the energy for all that.

So has anyone got any ideas of how I could make my home look less bare?

Sometimes it looks sterile. I really need some stuff to brighten the place up.