Rebecca, you’re right…as always :).
Ha, I’m not nearly always right, but thank you. 
I’m getting a little depressed now, though. People always used to say I was good at drawing and if I work something out in detail I know I can make it look good.
However if I get back to these basics everythings looks totally clumsy, like the work of a four-year old…
Yeah, these beginning stages can be painful, I know. But I honestly think they help the final, rendered product look better. Psychologically if it helps (I know I play a lot of these tricks with myself to avoid getting bummed) render a tiny area, just show you know what you are shooting for in terms of the finished look ~ maybe even do this is a separate document. That proves to the part of you that’s getting depressed that you are good at rendering, and allows you to continue at the comping stage without erroneously thinking that you ‘can’t’ draw. 
I’m going to try again, I already read the tutorials but I somehow just don’t know what something looks like until I work it out in detail. Hmmm…I’ll try harder.
Why not try a detailed comp, just small?
BTW, all of these are only suggestions. We all work best in our own ways, so none of what I am saying is something which you have to do.
Don’t let me interrupt your process as you are the one who knows how you work best. 
Cheers, 
~Rebeccak