The First Astrological House - Horoskopos
If you haven't read Robert Schmidt's article explaining the applications of topical houses vs strength divisions you might want to do so now, before proceeding. For novices, the descriptions below will give you insight into your own chart, but you will gain more knowing the difference between strength and topical divisions. I personally believe that reality cannot be rigidly measured and quartered off to the nearest minute of arc, so I do not bother with all of the different types of trisection of the 4 angles. Many of these house systems probably arise from a misunderstanding of previous doctrine, especially Ptolemy, which was easy to do because Ptolemy's greek was among the most obscure and convoluted of writings from the entire Hellenistic period (as Schmidt has already explained).  My approach is to use the whole signs, meaning that if Gemini happens to rise and the 24th degree of that sign is where the ascendant is placed (also called horoskopos), then the 1st house is from 0 degrees Gemini to 30 degrees Gemini, the second is the whole sign of Taurus, etc... To me this makes sense because the rising of the signs describe a process, the sign being the topic and the exact position of the ascendant where we are in that process/topic. This is most easily seen in horary astrology, where a late degree ascendant means something nearing completion, an early degree, just getting started, etc... In the case of the MC (median Coeli - or midheaven), this sign, if it happens to fall in the 8th, 9th, 10th, 11th or 12th place from the horoskopos, then I just include that sign in the determination pointing to career. I do the same with the I.C. (imum coeli, or 4th house angle), if it should fall in the 5th sign then I just say that the 5th sign also has to do with domestic, and ancestral matters. It seems obvious to me that the meanings gradually shift and heavily overlap eachother anyway. In many of the delineations below, I present extreme cases so you can get the full flavor of the planetary representations. Keeping your expectations more moderate, you will get a more accurate perception of the degree.
The First House: Also known as the horoskopos, or helm.  This is the place where the heavens come from the invisible into the visible, just as you came from the invisibility of your mothers womb to the visible world outside, from water to air, and then you took your first breath, marking the katarche (ruling beginning, or inception) of your life. For this reason, this place represents your physical body and especially the decan (face) of the horoskopos, your appearance. It does not necessarily represent a concrete physical appearance as this has more to do with heimarmene, but instead, the vital energy that you put out into the world. For that reason, if at birth, the lord (or almuten in medieval times) of this place is struck down, the ancients said that the infant is unreared or dies quickly. Should the lord of this place be received by benefics or essentially dignified, their vitality remains constant. In those days (or in modern 3rd world nations) the infant mortality rate was much higher and the physical determination much more difficult to overcome; so now the energy tends to work itself out in a wider variety of ways rather than just the first rule, which was to survive.
In a more literal sense, the "helm" is the steering wheel of the boat and the steward of this place (house lord) is the helmsman. If the helmsman is not at his station then the ship tends to run aground or sinks.  This is analogous to an individual with a lack of a clear direction who runs into trouble alot. In astrology, this is represented by the lord of the ascendant being in aversion. This happens when the ascendant lord is in the 2nd, 6th, 8th or 12th houses. It can also mean not having an advocate in life, since the house lord is the one who sees that the issues of that place get a hearing in the court of the cosmic consciousness. If the domicile lord of this place is exalted, then the cosmic soul sees this native more clearly and the life of the native will become more eminent. The bound lord would then set the standard for precision of steering the ship on the life journey. The trigon lord then uses the astrolabe to see if the ship conforms to the "course". 
More info on each of the planets that have dealings with this place:
1. This is one of Robert Schmidt's hobbyhorses. He frequently opens up with the difficulties of the Greek in his translations.
2. Paulus Alexandrinus. Introductory Matters 378 A.D. © 1993 Robert Schmidt, through Project Hindsight, Published by The Golden Hind Press. See pg. 50.
3. This is Schmidt's working out of the metaphor in his July 2000 lecture series in Cumberland MD.
4. From Schmidts lecture in Cumberland, MD in June, 2000.