Previously I wrote about the connection between being considerate and being conscientious without defining what I meant by the term considerate. To be considerate is to refrain from behaving in a way that suggests that you failed to consider the negative impacts upon others before speaking or acting. Sometimes, however, not speaking or acting might be inconsiderate when it would be of benefit to others for you to do so. This thoughtlessness can be a result of apathy, selfishness, or mere ignorance.
Avoid being oblivious to the state of others to reduce the risk of being unintentionally inconsiderate. A simple example would be making loud noises without noticing that someone nearby is on the phone. Another would be to fail to express an appropriate level of gratitude for a gift or favor because you were unaware of the substantial cost to your benefactor. A more complicated example might be to criticize someone for their lack of productivity at work while being clueless about their personal crises at home.
You cannot always predict ahead of time whether what you say or do will hurt or inconvenience others. Attempting to do so might cause you to freeze up completely. You can, however, respond positively when someone brings an issue to your attention by assuring them that the harm was unintentional and that you will avoid repeating the mistake in the future.
For more thoughts like these plus some quotidian, please see my paternal advice website. I have been adding everything I can think of to it recently, including the kitchen sink.