Get yourself a soft nylon detailing brush like the one below...
It can be bought here:
http://www.carcareonline.com/detail.asp?product_id=17626
Here's a high end version of the brush above:
And it can be bought here:
http://www.carcareonline.com/detail.asp?product_id=11174
These also work (but I prefer the nylon brushes):
And can be bought here:
http://www.carcareonline.com/detail.asp?product_id=19505

It can be bought here:
http://www.carcareonline.com/detail.asp?product_id=17626
Here's a high end version of the brush above:

And it can be bought here:
http://www.carcareonline.com/detail.asp?product_id=11174
These also work (but I prefer the nylon brushes):

And can be bought here:
http://www.carcareonline.com/detail.asp?product_id=19505