FF, this isn't a sticky, but basically I would recommend this protocol:
1. Get a good grasp of the person's chart so that you have a sense of what this person is like. Even if s/he has talent in a particular area, if it doesn't meet the individual's core personality needs, s/he won't be happy in it.
2. Get a good sense of the different planet, sign, and house rulerships. What does each of these entities cover? A good desk reference is: Rex E. Bills, The Rulership Book
, published by the American Federation of Astrologers. Although it is arguably out-of-date for the IT age, it is still in print and otherwise very comprehensive. Most job titles will be listed here. For example, surgeons, soldiers, and athletes are ruled by Mars. Higher education is a 9th house matter. So is overseas travel.
3. The 10th house and MC indicate career in the sense of a vocation, public image, or even destiny. This is not the "just a job" house: that would be the 6th house. If the person needs to live on the income from the job (and who doesn't) then also look at the 2nd and 8th houses.
3. What planets--if any-- are in the 10th house, and what are their aspects like? These tell you that the career is a particular focus for the individual, and the aspects tell you whether the individual is likely to experience them as stressful or harmonious. For example, if Saturn in the 10th is well aspected, the person probably has administrative ability. If Saturn in the 10th is stressed, the person probably feels frustration and inadequacy in his career. This doesn't mean s/he cannot be successful at it; merely that the career will probably be a stressor.
4. What is the ruler of the sign on the house cusp? If there are two, I would suggest looking at both the traditional and modern ruler. Then what is this planet doing by house and aspects? For example, if someone has the ruler of the 10th in the 5th, there are several options. (1) The career has to be fun for the person and a source of creative expression. (2) The person may not be best suited to a career, because the core meaning of the 5th is leisure-time activities and children. If this is a parent of small children, maybe s/he would be happiest staying at home with them--hopefully with the other parent bringing home the income. Recall that one meaning of the 10th is "public image" so this parent may be well known in the local PTA or scout troop as a super parent, not as a CEO or foreman. (3) The person might be good at a 5th house type of career, such as working in a municipal recreation program, the theatre, a gambling casino, or pre-school.
So for example, we could imagine someone with the sun in Leo in the 11th, with Cancer on the cusp of the MC. The ruler of the 10th house, the moon (in Pisces), is located in the 5th house. This person might make a good teacher because the Leo sun likes to be on-stage unless afflicted--and in a classroom the teacher always has an audience. The 11th house deals with friends and hopes for the future. An organization like a school offers friendships with co-workers and hopes for the students' futures. (We note also, that theatre is a 5th house matter.) Then Cancer and the moon have a parental or even nurturing quality, and this moon is located in the house of children.
4. Do the same thing with the 6th house of work and service, and the 2nd and 8th houses of money (the individual's plus "shared resources.") The 8th would be especially important if somebody was interested in an 8th house career like financial advisor. If the ruler of the 2nd is in the 4th house, for example, perhaps this person would prefer to earn money from home, or perhaps have a career in real estate or in an industry dealing with accommodations such as hotels.
It is kind of a separate topic, but if someone's money house looks stressed (for example, Saturn in the 2nd square Pluto and the ruler of the 2nd,) they really need to develop some personal finance management skills.
5. It is a big help to (a) know what careers are out there, and (b) what the day-to-day work is like. Also, it is hard to tell from a chart unless you are a better astrologer than I am whether someone has been to university or has the financial means to go if it is a younger person. Then some careers require advanced degrees, which might be difficult for an older person with stressed 9th and 2nd houses. Sometimes people are motivated to be spiritual teachers or tarot card readers, but they would usually need some other day-job to pay the rent. It is always OK to ask the person what education and job experience they have to date, and how happy they were with them.
6. There are a few wild cards in the deck. If people have artistic talent, they often want to express it regardless of whether it seems like their dream career to an astrologer. If someone has a "splash" type of chart without a discernable focus, they would probably do best in a job that has a lot of diversity and requires a "jack of all trades." If someone has a big focus on just a few signs and houses, they would probably be most motivated in these areas, even if his MC says something else. Also, squares are stressors, but they indicate areas of life that the individual is forced to develop, and an ambitious person may even select a job that accentuates her squares. People with watery charts might look super at working with prisoners or autistic children, but sometimes they will tell you no--they are so sensitive that their nervous energy would just get overloaded in absorbing these people's energy. If someone has the sun in an intercepted sign, Neptune in the first house squaring the MC, or other indicators of difficulties in developing a clear sense of identity, these people may feel they will never find a fulfilling career.
Some careers are really difficult to see in a natal chart. The Astro-DataBank at www.astro.com
is full of actors' charts. There does not seem to be much commonality between them.
7. Let your mind be open to different unusual combinations. If someone has strong 10th, 9th, and 8th houses that are not too airy, he might be good at a career in international trade. For an airy person with this combo, however, they might enjoy working in a university, even as an academic support staff member working in the financial aid (8th house) department or with administrators. A psychologist dealing with clients on a one-on-one basis might be good with Pluto, Mercury, and the moon on her AC/DC axis.
We can also look to the north node of the moon, to see where the individual's growth lies.