Minderwiz
It's progress indeed when you realise that the "Mars=Aries=First house" approach is actually stunting your astrological development. I fully agree with your sentiments. To me it doesn't work on any level (but one that I'll mention later in this post). Planets, Signs and Houses are all different entities and to conflate them is grossly misleading and actually confuses students in their later development. The linkage seems to stem from Medieval Medical Astrology, where both Signs and Houses were used as indicators of body parts, so, for example Aries and the First House were both taken as significators of the head and Pisces and the Twelfth House were both taken as significators of the Feet but that is the only linkage I've come across in the history of Astrology till the present day.
It's important that you recognise the difference between 'significator', 'analogy' and 'equivalence' - for example, I might say that my car might 'go like the wind' but it obviously is not the wind and you wouldn't really believe that is what I meant. Or I might do a Horary reading in which Mars is the significator of a lost book but clearly Mars is not the same thing as the lost book. The First House and Aries both share the property of coming first in order but that doesn't mean that they are equivalent.
For future reference, there's some interesting work being done by Chris Brennan, who is researching into Hellenistic Astrology. He's developing a very convincing theory that House meanings originate (at least in a large part) from the concept of the planetary Joys, which actually associates Mercury with the First House (The Moon with the third, Venus with the fifth, Mars with the sixth, the Sun with the ninth, Jupiter with the eleventh and Saturn with the twelfth). There's also early Hellenistic Texts which give the natal chart for the world as having Cancer rising (not Aries) and from which the planetary sign rulerships are derived. Don't chase those up now, I simply mention them to help make the point that many of the attempts to simplify Astrology or 'rationalise' it can actually damage its practise.
House systems are best left for a little while till you get into being able to read a chart with at least an established approach (even if you are still consulting your guidelines all the time). You will find that usually a change of house system will alter the nuances, or perhaps give different nuances, but essentially leave the reading the same. So wait till you are ready to add nuances, or till house systems begin to be something you're interested in.
By now you should realise that there are different approaches to Astrology, both in terms of what I might call 'schools of Astrology' and also at a personal level. Many books and websites are based on the Psychological approach and make use of Jungian ideas. That approach has dominated Astrology since the mid 1950s and most practising Astrologers grew up in it. If you are interested in the psychological side of Astrology it can be very useful but it is not the only approach, either in the twentieth century or in the history of Astrology.
Knowing what you base your Astrology on and why, like ravenest does, will come in time and indeed may shift over time as your interests diversify - until then, don't take anything as being the 'definitive way' and, as you are doing, keep asking 'why!'
He must be well-regarded, though: last year I went to a seminar during my first burst of true study of astrology, and while the subject matter was largely way over my head at the time (it was about hermetic lots, I believe was the phrase that was used -- it dealt with things like the Part of Fortune, Part of Spirit, Part of Eros...), the presenter did mention Chris Brennan as someone deserving of high marks in the field. I went home and bookmarked his site, and still have it bookmarked, although it hasn't been one of the ones I've been leaning on heavily yet.