Dont do any hard braking, or any long breaking. You want to wear them in without excess heat, both of the above will do just that. You want heat, but not lots.
The principle of bedding is is to match the 2 faces, and transfer material, the slower and more lightly you do this the less chance of putting too much heat in to them, which will cause the pads to glaze.
This is easier when you have new discs and pads as both surfaces are dead flat, so a closer match, Its more important to be careful when just changing pads, as disc surface is more likely to be uneven.