Mix dry ingredients. Add wet ingredients, not including frozen fruit. When everything is mixed well, gently fold in the frozen fruit soas not to break the raspberries and blueberries. If added when still frozen, they will remain whole and pretty and the dough will not stain.
Decrease the amount of sugar depending on the tartness of the berries. My berries were particularly tart so sugar should be decreased to 1/2 to 3/4 of a cup if your fruit is sweet.