I love this initial photograph of my beautiful model Lydia; (don't you love her natural hair? I do!!) you can see the beautiful grasses behind her and there’s nothing really wrong with this photo, but do you feel how intimate this second one seems? Her eye is where you’re immediately drawn and you feel like you’re there with her. It’s okay that the top of her head is cropped; that’s what makes the portrait feel intimate, like you're sitting there with her.
To avoid distortion in the features of the person you’re photographing, you’ll want to back away a little bit. Whatever feature is closest to the lens is going to look larger than usual, so you’ll want to back off from the person and then crop in on the image. You can choose to get as close as possible to distort features on purpose for a more comic effect.
1. When you crop in on people, take care to avoid cropping at joints; otherwise, it can look like your subject is missing an appendage.
2. Don't be afraid to crop off the top of the head if it's an up-close portrait; this adds a feeling of intimacy to the portrait.
3. Most of the time, if you're photographing children, getting down to reach eye level with them will look amazing; you'll really be able to feel the connection through the photograph.