In addition to the answers you have already received, I would like to make some clarifications:
Once you have applied yourself to astrological studies made available on JoS, it will be easy for you to understand paragraphs like this:
"Knowing an enemy's date of birth, you can work black magick with the energies in their charts. Whenever someone has a retrograde Saturn period (we all have this), you can direct the negative energy to your own purposes for revenge. The universe is working against this person during a bad Saturn transit. Saturn retrograding over personal planets, through the first house or to a lesser extent, on the progressed planets, this is the worst time of one's life. The worst of all is Saturn retrograde on the chart ruler; you can only know this by knowing the birth time"
Here you can calculate people's transits (even yours):
Joy Of Satan Astrology Project
www.jos-astro.com
The Satanic calendar shows the periods in which the planets are retrograde:
Joy Of Satan Astrology Project
www.jos-astro.com
The roles of some planetary transits are well explained here:
However, I advise you to study the entire astrology section first, so you have a clearer idea of what you are doing and know the general framework in which your specific question is inserted:
Another way to use people's birth dates with astrology is to know the weak points of your enemies, reported in their natal chart, to curse them there with your black magic:
Joy Of Satan Astrology Project
www.jos-astro.com
I didn't quite understand what you mean with your question about planetary influences, in any case here you can see what the various planets govern:
Finally, in answer to your question about what you should pay attention to: I would PERSONALLY suggest you pay attention to VARIOUS transits and planetary aspects. Don't look for things specifically without putting them in context.
For example, perhaps a planetary aspect of your enemy's birth chart shows you that he has low self-esteem and tends towards depression, but perhaps other aspects of his birth chart can lead him to have strong self-esteem and perhaps these last aspects are the strongest (i.e. have greater influence on his soul).
So analyze everything carefully and don't limit yourself to just looking for a few specific aspects. Maybe there are things that "cancel" each other (in a certain sense).
Before understanding my entire answer, however, you need to study Azazel's Astrology section for Satanists carefully!