Ticks hitchhike on wildlife and can reside on bushes. Fleas like to be where pets lay the most. In kitchens, flies are indicative of a serious sanitation issue.
Bifenthrin is a common acaricide for tick control, especially recommended in liquid solutions, but be sure to rotate with other active ingredients as needed. For fleas, clean pet bedding regularly, and recommend clients speak with their veterinarians about appropriate flea control medications for their pets. Outside areas also can be sprayed with a residual insecticide every couple of months.
Flies are more complicated, but a proper IPM program with a strong emphasis on sanitation is the key.