Use a shampoo labeled for cats or dogs; never use shampoo for people on your pets. Begin washing your pet's head and neck first so the fleas don't jump up into its eyes, mouth, and ears. Bathing your pet any more than once a week could lead to skin irritation. Using moisturizing shampoo that contains oatmeal can help prevent your pet's skin from getting too dry. At least once a day, run a fine-toothed flea comb through your pet's dry fur. Periodically dip the comb in a cup of hot, soapy water or a 1-to-1 mixture of alcohol and water to kill the fleas you pick from the fur. Watch out for fleas that jump off of your pet. While your pet's coat should be dry, a bathtub is a good place to groom it. You'll have an easier time seeing fleas against the smooth, white surface. Slice a lemon thinly, and add it to pot filled with 1 US pint (470 mL) of water. Bring it just to a boil, then remove it from heat, cover it, and let it sit overnight. Strain the liquid into a spray bottle, then spritz your pet and massage the solution into its fur.  You could also purchase a citrus pet spray online or at a pet store. Citrus can deter fleas for up to 24 hours, but daily applications could irritate your pet's skin. Try spraying every 3 or 4 days, and gradually spray more frequently if there are no signs of skin irritation. Avoid spraying near your pet's face. Discontinue use if you notice red or dry skin, or if your pet scratches itself persistently. It's always best to consult your pet's vet before treating it with a home remedy. If you have a cat, it's best to keep it indoors at all times. If you have a dog, take it outside for short potty breaks. When you take it out, avoid shady, damp areas with lots of overgrowth. Limiting the time your pet spends outdoors will help reduce its exposure to fleas.

TL;DR in Vietnamese:
Tắm cho thú cưng ít nhất mỗi tuần một lần. Chải lông thú cưng hàng ngày bằng lược chải bọ chét. Thử xịt dung dịch cam chanh lên thú cưng. Giữ thú cưng ở trong nhà càng nhiều càng tốt.