If you wish to take decent pictures without flash, you must take the pictures outdoors with sufficient natural light. Without meters, you'll have to be the best guessor on f-stop and shutter speed. You have to learn how to read your in-camera meter to get the proper exposure. Indoors, you must use flash, studio lights, or strobe, otherwise you will not get any image on film. Portrait photography indoors is very dependent on placement of lights to get the proper effect such as highlights and shadows.