Follow rules

Pic source: https://www.team-bhp.com/forum/ride-safe/147027-helmets-testing-procedures-standards.html

It is recommended to use all of the gears as mentioned in the above picture when you know what road you will be travelling on highways. Least recommended is helmet and shoes when happened to travel for short distance. If i recall my accident in 2015 (which has a major accident), though I was maintaining my lane discipline the truck driver's visibility could have been a major reason for my accident. when I fell over the road my head got protected from the impact. I was fortunate to wear my helmet. The above helmet was the real saviour. 

Head injuries are the vital reasons for any person to get killed in any minor or major accident. Do you want to know how helmets are tested? watch the below video. 

Do you want to understand why the government enforces public to use ISI certified helmets? Because there is a certain procedure that ISI standard follows which is given in IS-4151 - 7 Protective Helmets for two-wheeler riders. 

These are the test done by the certifying authority for the product.

a) Impact absorption test has been modified with a number of additional impact points, use of kerb stone anvil, increased impact velocity and head injury criteria etc.

b) New tests to simulate the abrasion of helmet, chin guard and for the effectiveness of the retention system.

c) The inclusion of side impact test under various conditions of temperature

and humidity.

d) Allowance for ventilation of the head, while wearing the helmet.

There are other agencies such as SHARP(Safety Helmet Assessment and Rating Programme) which tests the helmet. SHARP provides advice on how to select a helmet that fits correctly and is comfortable and information about the relative safety of helmets to help motorcyclists to make an informed choice. https://sharp.dft.gov.uk/