First thing first, you have to turn on the water tub and set the temperature as per your requirement. Here, the water should not be too hot for the baby. So, you can consider heating it up a bit lower than you usually do. Fill the tub completely, as you do in your normal routine.
Now you need to take infant seat/bouncy chair and place it right next to the tub on the floor. Take baby's towel and lay it open on the chair. If you do not have a baby chair, then you can also lay the towel on the floor.
Take off baby's clothes and set her on the towel in the chair. Unfasten her diaper but leave it under her to catch any emergencies.
Get into the tub and relax. Here, you can consider reading a newspaper of a magazine of your choice. The baby will enjoy being next to you in the bathroom, able to see you while you wash your hair or soak.
As the water cools off and your baby gets antsy, lean over the tub side and pick up your baby, leaving the diaper off. Gently introduce her to the water, bringing your knees up in a way that she can rest on your lap, against your legs.
Wash and enjoy time with your baby. Let her splash in the water. When you are ready to get out, lean back over the tub and put her on her fresh towel on her infant seat, wrapping her up. Then get out of the tub yourself.