Not shooting in RAW!
You must always shoot in RAW. Shooting RAW makes your picture get in more fine details of the scene, you get a better quality picture in the end which won’t degrade to a much lower standard when you do exhaustive post processing later. Make sure that you use an editor that supports RAW images having the extension of .NEF. I use Adobe Photoshop Lightroom.
Shooting in only one mode
Some DSLRs come with a mode named AV which means you can set your own fixed value for f-stop aka aperture. While in manual mode, you have to adjust the rest of the settings like ISO and shutter speed to match your aperture but in case of AV mode, the camera does the work of computing other settings automatically according to the aperture set by you. This technique can come in handy when you want a consistent blurred background in all of your pictures and you’ve to snap randomly, not having the time to set all the things every time.
Pay more attention to your background
By this, I not only mean to get a beautiful backdrop for your pictures but also to make sure nothing obstructs your subject or the person in the frame. Lines and objects placed touching the body of the subject look not so pleasing. You can use the background to your advantage, find a naturally occurring frame like a window or a mirror that draws more attention to the eye. People’s eyes should be drawn to your subject in the picture in an instant.
When the pictures are overexposed, the highlights are lost forever. You can’t get them back in post-processing as well. On the other hand, if the pictures are underexposed, it’s no such a problem. Shadows store the details which can be regained in post processing easily but once overexposed, there is no coming back.
While shooting pictures this detail can sometimes go unnoticed. Hold the camera with both of your hands with a steady posture. You can also enable the grid on your DSLR screen to help you get straight images in a go.
If you are taking pictures on the go where there is a lot of movement in the frame, always set a higher shutter speed to get that crisp looking picture. Blurry images aren’t what any photographer would want, sharpness intrigues.