Rinse the freshly washed panel off with fresh water, then wet and wring out the DeBugger cloth with fresh water, fold in half and spray 5 to 6 sprays diectly into the cloth surface and use it to gently rub off the bug marks from the car. Keep turning the cloth to a clean side with each wipe, and rinse the bugs off with water once it gets full.
If its really a really bad level of bug splatter, liberally spray the Bugger Off over the still wet, affected area, doing a small section at a time. Focus on where the bugs are most concentrated. Let the product sit for about a minute, spraying a little extra if it ever looks like it's drying. Then as per above, wipe over with a damp DeBugger cloth.
Rinse the cloth out in fresh water and wipe over the area once again, before finally rinsing the panel clean with fresh water. Then chamois/microfibre towel dry the front of the car and you're done.
I know plenty of professional detailers who like to use a pressure washer for this job, using the strong stream of water to remove the Bugger Off and all the bugs with it. I must say it does this job well. However, the bugs that remain can get pushed back into the grill and other innards of the car, meaning there can be more cleaning later, in areas that are very difficult to access. So try and make sure the water pressure is directed away from those areas.