So let's take a leaf from an age old cleaning method. Here is what you should do.
1. Remove DSLR lens and tilt the camera downwards (as seen in the picture above)
2. Use blower and give it a few shots of compressed air
3. Repeat when necessary.
Why dust gets trapped in the cavity is simple, you often change your camera face up. Dust as you know will eventually land somewhere and by changing your lens face up, you are actually CAPTURING dust instead of dispelling them.
Once the minute particles gets into the camera cavity, your images will show up little specs of dots. The anti-static charge has been proven to be ineffective, and you will need to clean your sensor with a blower when possible.
Blowing your camera cavity tilted downwards is far better option than blowing it facing upwards. Newton's law applies here regardless of what you think of the wind and the weather. This simple procedure when done correctly will save you a heap of problems later as sending it in later for professional cleaning is a costly affair.