Always stand straight to avoid the pain in the back. Your chin should level the ground, and belly should be tucked and shoulders at the back.
Posture friendly props such as an ergonomic chair helps maintain good posture and supports curvature on the lower spine.
Slouching on the chair, bed or anywhere is bad for your posture as it might hurt your back in the long term. You must sit upright at a 90 degree angle and feet flat on the ground.
To avoid pain in the spine, one must avoid overprotecting postures. Relax your body as restricted motion can cause problems in the long term.
For a good posture, select a mattress which is firm as it will support the actual posture of the spine. Placing a pillow under your neck is a good option to maintain the posture.
Lowering the neck while reading texts or texting puts a lot of pressure on the spine. Make sure to stretch your neck and keep the phone at eye level.
When you are sitting for too long it might tempt you to slouch. Hence get up and move to maintain your posture.