Before you start your DIY:
Control the supporting wall
Make sure you know what material the wall is made of, and what the optimal type screw is for that material.
Control the floor...
Your wardrobe will be resting on the floor, which will need to be level to make a solid foundation. You also need to take the final floor surface into consideration: carpet, tile, hardwood,etc? How will it meet the wardrobe? Will the floor get a new finish after the wardrobe, or does the wardrobe stand on it?
...and sometimes also the ceiling
If you are installing sliding doors, will the meet the ceiling? If so, do you have what is required for that contact?