A common mistake that I've noticed with beginning students of Jyotish is to just look at the 10th house, the 10th lord and the karakas or significators of the 10th house for determining career. However, before examining any house in the chart we need to realize the importance of the lagna (also known as 1st house, ascendant, or rising sign), which represents the self and one's main character traits. It's the basis, or vantage point, from which we view the world and colors all areas of life, including career. How we approach any area of life will be affected by the lagna, and any area of life can be seen through it. Collectively, the lagna, Moon, and Sun, represent one's personality more than any other indicators in the chart, with the lagna (and lagna lord) being considered the most important of the three.
The following chart is of a woman who's spent most of her adult life as a real estate broker. This, you might say, is obvious because Mercury, the 4th lord representing home and real estate, is in the 10th house. Yes, this is true, however Venus and Saturn, the rulers of the 5th, 12th, 8th and 9th houses respectively, are also in the 10th house. Why wouldn't this person be an artist, for instance, with Venus, the planet of creativity, and ruler of the 5th house of creativity, in the 10th house? Furthermore, Venus is exalted in Pisces. Certainly, a case can be made for an artistic career for this person.
Natal Chart of a real estate broker - example 1
It's because Mercury is also the ruler of the ascendant, which is no small point. Mercury rules sales and marketing. This woman told me, "I've been in sales my entire life." Mercury's placement as the 1st and 4th lord in the 10th house certainly inclines her towards sales, particularly sales in real estate. This becomes further reinforced because Mercury also exchanges signs with Jupiter, the 10th lord, forming a parivartana yoga. In case you may be thinking, "But, wait a minute, Mercury is debilitated in Pisces!" Mercury is also in a neecha banga raja yoga, canceling its debility, due to its conjunction with an exalted Venus.
Here's another chart of a person with Gemini lagna, who has also been a real estate broker most of his adult life. However, this time Mercury is not even in the 10th house. Mercury does, however, become very strong by being in its own sign in an angular house, forming a bhadra mahapurusha yoga. This heightens the strength of Mercury as a salesman, and as the 1st and 4th lord it inclines him toward real estate. This becomes further reinforced because Mercury is also aspected by Jupiter, the 10th lord.
Natal Chart of a real estate broker - example 2
In 1988, in his Saturn-Rahu dasha, he began his own real estate brokerage firm. Rahu is aspected by Mercury, and ruled by Jupiter, the 10th lord.