I've implemented a hierarchical data structure for the bodies in a solar system: center-of-mass, star, planet, moon, etc.. I've then studied how bodies orbit around each other, and which parameters affect the body's motion. A good dose of patience was necessary, and some notions of astrophysics needed.
Well, here i am. After i finished my code, today, i plugged in the orbital elements for the main planets of the solar system, and entered a date. I then compared my results with a diagram i found over the web, at approximately the same date. The results were matching! Houra!
However, they are matching.. but not perfectly. I guess this is coming from a lack of precision in the calculations, and mostly from a lack of precision in the initial conditions/orbital elements. If somebody knows some good sources for orbital elements of the major planets, please let me know! I've found quite a few ones on the web, but they do not always agree, so i'm unsure about which ones i should use.
I've also been working on generating the solar system procedurally, with some pseudo random functions. Lots of research is needed, mostly to get correct statistics about the population of stars / planets ( and their parameters ) in the galaxy. I'm aiming at making a semi-realistic galaxy (err: i should say believable).