I wish I could say its easy but in true astrology it isent. Like anything it takes patience and effort to do.
I can assure that it is not your sun sign you look to. In general You look to the ruler of the ascendent and its sign as well as to what sign the moon is in. This is general of course, as the rest of the factors are derived from the persons temperament (Latin for mixture) which plays a part in not only the persons inate qualities that they are born with but also the persons physiognomy as well.
To explain every little detail is not really possible here but I would be happy to list my sources, I dabble in traditional astrology, the astrology as was practiced before it was corrupted by theosophy, Jungian Psychology ect.
Finding the appearance of the person can be done and using traditional means is far more accurate than the corrupted techniques today. Also there are bound to be things that are alien to you but my intent here is speak the truth, if you do not understand everything I say than you will have to look them up (I have links for that).
Some techniques for temperament are as follows: 1.First off is to note what sign the ascendant is in, next you must find the ruler of the ascendant, than the almuten of the ascendant. The almuten is the planet with the most essential dignities. (link explaining this below)
2.Look to what sign the moon is in, after that look to what planet rules the moons sign, than look to the what phase the moon is.
3. Look to what sign the sun is in, here you do not look at the qualites of the sign but what SEASON the sign is in Aries, Taurus and gemini are spring signs, etc.
4. Look to any planets in the first house, as well as planets aspecting the lord of the ascendant and the moon. After all these are noted you are to collect all of testimonies together and judge.
PS No doubt you are confused some sources to look to for clarity are these. copy and paste.
Read this first it is excerts from the book I own where much of this info came from.
http://www.skyscript.co.uk/temperament.html
Next go here:This explains the temperaments brief as they are:http://en.wikipedia.org/wiki/Four_Temperaments
For dignities go here: http://www.skyscript.co.uk/dignities.html


