The wire frame is a big help on a lot of placement issues. Also you have to take into consideration when you are trying to create a real scheme is that as cool and accurate as the models are they are not 100%. You have to make concessions on some things.
The biggest help and really the thing that most people have the hardest time figuring out in the beginning is learning how to use the pen tool. I also struggled with this but learning how to use it will greatly improve your abilities. Whatever paint program you are using, do a google or youtube search on how to use the pen tool to get an idea of how best to use it.