I've used it a bit and at first had the same problem as you. The thing is you have to think about drawing things differently than you would by hand. I found the tutorials very useful, so I suggest you watch them. I think you might find it's easier not to draw seperate parts and then try to put them together, but if you realy need to,then watch the sketchup tutorials on 'inferencing' and 'inference locking' . Make sure you watch them all the way through as it may seem like it doesn't cover what you need to do to start with, but it gets there.
Last edited by gav; 01-28-2010 at 11:44 AM.