The Lord taught:
20 Behold, this is your work, to keep my commandments, yea, with all your might, mind and strength.
21 Seek not to declare my word, but first seek to obtain my word, and then shall your tongue be loosed; then, if you desire, you shall have my Spirit and my word, yea, the power of God unto the convincing of men. (D&C 11)
As you completely obey your best understanding of God’s will for you in all things, he will give you more light. His word is the light and it will reveal things as they really are.
As the light within you grows brighter and brighter, you will find that as you interact with the world, the light reveals to you how things as they really are differ from things as they seem to others. The light within you will provide a different perception, and this different perception will yield suggestions for how to change behavior and belief to interact with reality more accurately.
For those that have experienced what is described here, they will be very familiar with the burning feeling that comes when a better outcome is possible, but unseen, except in the light inside you.
For those who are unfamiliar with what is described here, imagine the last time you interacted with the black sheep in your family, or the friends you have with rotten kids, or some other similar situation where it was abundantly clear that there was a better way to do something that would result in the alleviation of many of the negative consequences tied to the present situation. Recall how you could see that there were specific beliefs about the situation that were causing the undesirable outcomes, and how intensely you wished that you could help the people involved to know what you knew.
This is what it is like to have more light inside of you. As the light grows, you will feel this way in more and more situations. It is possible to come to the point where you feel like this in every situation: where the light God provides shows you the difference between the present, telestial (or worse) situation, and the celestial alternative.
As a light bearer, your responsibility and privilege is to bring about the celestial alternative to the present situation to the greatest extent possible, given the constraints of the choices and desires of the people involved.
There are two ways of doing this. The first is to teach what the light reveals to you. The second, which is both far more difficult and far more beneficial, is to teach them how to obtain and apply the light for themselves.