I'm interested in converting a YT-1300 into a YT-1930 (photo below) but i have no idea where to start, (i have only limited experience working with plasticard), though i can do well enough pointing that that's not a problem when i get to that point

a YT-1930 for reference, ARTWORK NOT MINE

Check out Macross' thread. He often posts WIP images for his projects which might give you some direction.

Additionally, google YT-1300 conversions to see how to get yur Falcon apart.