I started a Lego model too. Using handbook from
http://www.hccamsterdam.nl/brickfactory/theme/index.htm (see in Technic #3) Many thanks to
andybuck for the idea and the link.
It appears that simple blocks & plates are easy. But for other pieces, pretty touchy stuff. Like many newcomers to Lego modeling I think, I use LDraw library for basic shapes & dimensions (for non blocks&plates parts). Every shape in it needs some serious work to be nice on screen (chanfering, mesh cleaning, etc. on a per-vertice basis)
As an example, in the two renders below, only "Brick" and "Pin" parts were reworked by my own fingers. I.e. red and lightgrey parts are out-of-the-box LDraw shapes.
Work in Blender (Yafray for rendering as usual) but importing shapes from LDraw using software I discovered yesterday, Leocad. A Linux version is available, it features Wavefront export (to reimport into Blender).