Although an old question, perhaps worth another perspective since this type of speculation often resurfaces.
On the most basic level, one could say that adhering to the 5 precepts, also contained in Right Action and Right Speech, goes a long way - if not all the way - to maintaining Right Livelihood.
Right Livelihood at its core
"And what is right livelihood? There is the case where a disciple of the noble ones, having abandoned dishonest livelihood, keeps his life going with right livelihood: This is called right livelihood."
— SN 45.8
So if the living situation is such, that you do no harm, by abstaining from killing, from taking what is not given (purposely not just 'stealing'), and from sexual misconduct, you are acting in accordance with the teachings.
And if the living situation is such, that when you speak, you abstain from lying, from speaking harshly or out of anger, from malicious or divisive speech, and from gossip and idle chatter, you are speaking in accordance with the teachings.
If living in a heedful way, not taking intoxicants that lead to carelessness in these areas, such as alcohol, drugs (or even medication), you are living in accordance with the teachings.
And if, when speaking of actions and speech like the above, you do not promote harmful action, harmful speech, and carelessness (like what's mentioned above), but you promote wholesome action, wholesome speech, and heedfulness, you are living in accordance with the teachings.
The balance of the middle way
"Herein, Vyagghapajja, a householder knowing his income and expenses leads a balanced life, neither extravagant nor miserly, knowing that thus his income will stand in excess of his expenses, but not his expenses in excess of his income.
"Just as the goldsmith, or an apprentice of his, knows, on holding up a balance, that by so much it has dipped down, by so much it has tilted up; even so a householder, knowing his income and expenses leads a balanced life, neither extravagant nor miserly, knowing that thus his income will stand in excess of his expenses, but not his expenses in excess of his income."
— AN 8.54
Simply avoiding extravagance and stinginess, the middle way of being heedful of income and expenses and not making purchases to show off or accumulate non-essential things. Dana - giving - is also part of wholesome living, although not mentioned here.
For lay followers to avoid
"A lay follower should not engage in five types of business. Which five? Business in weapons, business in human beings, business in meat, business in intoxicants, and business in poison."
— AN 5.177
Additionally, some suttas strongly suggest avoiding careers in the military (SN 42.3) and acting (SN 42.2). These are likely to be conducive to a rebirth in a hell realm.
