Making photographs of people indoors, which are in focus and sharp is a challenge. Here are steps, which will ensure your photos are first-rate.
The first step is setting your ISO on the camera to 400, 800 or even 1600. The less light you have available the higher the ISO number you will need. However, there is a tradeoff of quality as you raise the ISO number. Always go with the lowest ISO possible to make the photo for the best quality.
Next, be sure the shutter speed and aperture (ƒ-stop) properly set for the correct exposure. You will most likely need the widest aperture setting and need a lens with at least ƒ/2.8 or better. The rule of thumb for setting the shutter speed is to set it to the fraction closest to the focal length. If you are using a 60mm lens then your shutter speed should be at least 1/60 to minimize motion blur.
While your photos may now be properly exposed, they may turn out green, orange or even blue. Setting your white balance for the lighting conditions will correct this. Most cameras have preset selections for tungsten, fluorescent or daylight. Some will even let you custom white balance. Camera settings are different from camera to camera therefore you’ll need to check the manual for how this is set.
You may still have photos that look out of focus or not sharp. That’s due to two possible problems. 1) If the camera was motionless during exposure, the people may have been moving or subject movement and/or 2) the depth-of-field of the lens is too shallow.
A strobe would be helpful. A flash will freeze the people and allow a higher ƒ-stop/aperture allowing for a greater depth-of-field.
Direct on the camera flash creates harsh shadows. Dispersing (bouncing) the light off a matte, colorless surface like a ceiling will soften the shadows. Try using a flash with a swivel head upward and sideways for vertical shots to bounce the light off the ceiling.
Using an extension cord designed for your flash to get the flash away from the camera will give you even more choices by just holding the flash at arm’s length.
Even direct flash can look better when off camera.
Colors are more accurate when using flash. Full spectrum light is what a flash puts out and makes colors appear accurately in print. Other lights, like fluorescent or tungsten, only use a partial spectrum of light making it difficult to deliver accurate colors.
Take the time to practice these suggestions. Shoot without a flash and get the exposure and color correct. Try shooting with a bounce flash. You be the judge as to what is acceptable.