Non-reversible word pairs always appear in the same order, e.g., back and forth. It would sound awkward if we read forth and back. For many of us, certain words go together and we will automatically use the correct order. Collocations are also a good idea to learn if you are a non-native speaker.
The following is a list of common word pairs.

Bits and pieces – small individual things.
Eg- Students take grammar sessions in bits and pieces ie.thrice a week at Wabstalk.

By and large – mostly, generally with few exceptions.
Eg.-By and large the course duration of Wabstalk is 3-6 months.

Give or take – approximately, plus or minus some unknown amount.
Eg-The work will take approximately three hours to give or take a little more time.

More or less – mostly/ almost
Eg.- more or less all kinds of people come to Wabstalk the professionals, students, Lawyers, etc.

Part and parcel – an integral and essential piece .
Eg- Workshops are the part and parcel of Wabstalk

Safe and sound- safe from danger and free from injury and harm.
Eg.- Wabstalk provides a safe and sound environment for everyone.

On and off- intermittently
Eg- On and off Wabstalk conducts competitions outside the center.

Hustle and bustle- an activity or work that is done in a noisy surrounding.
Eg- Wabstalk classes are held away from the hustle and bustle.

Piece and quiet- a period of silence especially after a noise or stress.
Eg- The hill stations are the destinations which provide peace and quiet to the tourists.

Pros and cons – the positive and negative attributes of an argument.
Eg- We should weigh the pros and cons of the decision before taking any step.

Cause and effect – one event which leads to another event.
Eg- there is always a cause and effect of our action.