Next principle .....
Actually 2 principles.
(1) If the Atmakaraka is found in the Lagna of that divisional chart, then the perosn is lucky in the area of that divisional chart. What he is striving intensely for (Atmakakara) for his soul (the Sun) is easily obtained and manifested and plays a large part of his life. For the trines (5th or 9th), the context of the divisonal chart is also easily obtained, but may not be as large a part of his life as when the Atmakarak is found in the Lagna.
If the Atmakaraka and the Lagna Lord of the Rasi is the same planet in the Rasi, the person would further benefit from the above configuration, as in this case he is striving for his physical self (Lagna Lord) the areas under that divisional chart and with success. So he is more able to say, "Hey, this is really what I want. See how it benefits me physically."
(2) If the Lagna Lord of the Rasi chart (here the first basis is the Lagna Lord) is in a good relationship with all the other planets in that divisional chart (meaning there are no planets in the 6th, 8th and 12th houses from where the Lagna Lord is posited in that divisional chart), predict that the person will do very well in that divisional chart (if there are planets in the 6th, 8th or 12th to where the Lagna Lord is situated in that divisional chart, then the proportion of falling off of well-being for that person in that divisional chart the quantum is calculated accordingly). Planets ruling karya houses in that divisional chart should be given a higher weightage for this configuration Yoga.
Whereas (1) deals with easy access to resources of that divisional chart, (2) here deals with easy access PLUS kingship as well (meaning the person experience the FULL benefits of this divisional chart). If this Lagna Lord happens also to be the Atmakaraka, the benefits comes to him FOR SURE whether earlier or later part of this life.
Now in (2) if the chart happens be an overall chart like D-9 or D-60, look to which Bhava that planet rules in the Rasi chart. The person has success in those areas. So if Jupiter is in angles to the Lagna Lord of the Rasi chart in D-60 and Jupiter rules 9th Bhava and 6th Bhava in the Rasi chart, past life has given the person success in 9th Bhava and 6th Bhava matters. The D-60 should be given more consideration than for D-9, the Navamsa since in the Dasa Varga scheme, D-60 commands a higher weightage.
But since the Navamsa is a chart for fortune, happiness and luck, if the Lagna Lord is in a commanding position in the Navamsa (meaning none or very few of the planets are placed in a Dusthana position relative to it), it can still tide the person over any rainy days, even if the positions of the planets with respect to the Lagna Lord in the D-60 is bad (6th, 8th or 12th to the Lagna Lord).
Another overall chart which you may want to look at is the D-45 and areas where you want to expand towards (this again has something to do with your Lagna Lord) would be the D-40.