What are some tips and tricks to increase concentration power?

How to train your mind in 3 very simple steps:-

Count backward from 100 to 1. When you are able to do it without any distractions then only step forward.

Count backward skipping 2 digits ,like 100 97 94…so on. Step forward when you master this.

3. Take an apple or an orange. Just visualise it from all angles without having any verbal thoughts. Practice this and you will successfully master the skill of avoiding distractions in real life.

*Edit,for the people who didn't understand the point 3. Hold the apple in your hand ,rotate it, observe each and every side of it from top to bottom and from right to left. See the pattern of shades, the spots , the bumps, the curves ,etc if any. Imagine it in your head after watching it twice or thrice. That's how you focus on each and every detail of any subject given to you and in this case it is an apple.

*Edit 2- YES! You can totally have verbal thoughts only about the subject you are examining(i.e. apple ). [Thank you Manashi Sarkar]

Source: Experience.