Fabrics and paint
If you are allowed to decorate then you could paint the walls in neutral tones to freshen up the rooms and give you a blank canvas to work with.
Although you may not be able to change curtain tracks or poles you could change the curtains. You do not have to spend a fortune on these as you could look for some competitively priced designer clearance fabrics and have a go at making some simple pencil pleat curtains yourself.
Use fabric or pvc as a tablecloth to cover up ugly tables.

Throws and cushions
The easiest way to disguise a sofa or chair is to use throws to cover and update these and you can always take them with you when you move.
Adding cushions is a great and low cost way of injecting personality into a room - there are hundreds to choose from and you are sure to find something to suit you.
In the bedroom you will have chosen your own bedding so add more throws and cushions to add even more style.

Lighting and rugs
Lighting is often just a harsh central light bulb! You could add your own shade and also add table lamps in the lounge or bedroom to soften the lighting and add some ambience.
Rugs are a great way of covering up tatty carpets and adding colour, warmth and texture to your rooms.
Making a rental property feel like home is all about accessorising and choosing items which inject your personality into the rooms.