Soak the bugs with a wet paper towel for 10 minutes first.Use car wash soap with lots of water never, household detergent.
To avoid scratches dip you wash cloth ofter to remove any dirt particles which could scratch the bike. Start at the top and work your way down . I also use a wheel brush for the wheels and hard to get to places.
I use a spray on detailer wax after each wash, bike still looks good.