inpro,
I agree,
begin with the intent to draw it like it will be built. Modify and adjust only as the current limitations of AC dictate.
How far does the beam bear into the wall? Make sure the walls have the correct composition and sufficient bearing distance for the beam bearing specification. Then set the beam into the wall to the correct composite depth and the correct top of beam elevation to support the roof/floor above.
If you are just beginning the process of Modeling:
Look at this video by Eric Bobrow,
http://www.archicadtemplate.com/video-tips/trace2d/
HTH,
Snap