Buddhist literature doesn't say much about right livelihood compared with other factors of the path to liberation.
Right livelihood is the third factor of the Eightfold Noble Path (8FNP) having an ethical character. The other two ethical factors come before it in sequence so any livelihood that is not in conformity with the first two factors is also wrong livelihood. The first two ethical factors are right speech and right action.
Right speech was described by the Buddha, in The Discourse on the Great Forty (Mahacattarisaka sutta M117), as refraining from four kinds of wrong speech: false speech, malicious speech, harsh speech, and gossip.
Right action was described in M117 as refraining from three kinds of wrong actions: killing living beings, taking what is not given and misconduct in sensual pleasures.
Right livelihood was described in M117 as refraining from wrong livelihood that includes: scheming, hinting, belittling, pursuing gain with gain.
Right livelihood was also described by the Buddha, in the Numerical Discourses (Anguttaranikaya A5.177), as follows:
A lay follower (non-monastic) should not engage in these five trades. What five? Trading in weapons, trading in living beings, trading in meat, trading in intoxicants, and trading in poisons.
In other words the Buddha outlined wrong livelihood. He did not explicitly describe activities that are right livelihood. Many Buddhist lay followers (not monastics, not monks or nuns) traded goods and services that are not in the list above.
The list (in A5.177) of trades to avoid are obviously harmful to others and less obviously harmful to oneself. We can use common sense in those trades.
For example, although a car or truck could be used as a weapon, selling cars or trucks meant for transportation is not wrong livelihood. An example of dealing in human beings is buying, selling and using slaves for ones livelihood. If you knowingly include products and services created with slave labour as inputs for products and services you sell for your livelihood then one is doing wrong livelihood.
If as part of one's employment duties one speaks or writes falsely, or repeats falsehoods created by others, then there is wrong livelihood on those occasions.
Many livelihood activities are a mix of wholesome and unwholesome actions and results.
In an employee role there is scope for both right and wrong livelihood. Each person choose moment by moment to follow the 8FNP.
One person who tends to tell falsehoods for personal gain will frequently be doing wrong livelihood regardless of the specifications in their employment contract. Another person with more wholesome habits doing that same job might always be doing right livelihood.
A monastic monk or nun can also undertake wrong livelihood by hinting or implying that donations to them are especially meritorious without necessarily speaking falsely.
Right livelihood and the other factors of the 8FNP purify conduct and mind. The three ethical factors are the foundation for a stable and tranquil mind which is the basis for liberating wisdom.
Led by right view, the path factors of right effort/persistence and right mindfulness support the development of the three ethical path factors. By continuing to repeat, cultivate and develop all the path factors we set up conditions for awakening.
The Buddha taught us to figure out for ourselves the countless specific instances of right and wrong livelihood. These all require application of right view.
