Summer_doug,
If I go lightweight should I wrap with thread size A?
I have never used a thread heavier than size A in all my years of rod building, even on rods as heavy as line weight #10. If you were building really heavy blue water fly rod for a #12 and heavier line weight and big strippers and snakes, or all ring guides, you might want to use size D winding thread.
Do you have a thread spool tensioner? It is a gadget where you mount your thread and it has a spring with a wing nut and you can loosen, or tighten, the wing nut to control thread tension. It clamps to your work table.
When I didn't have one I would get a stack of hard cover books and put the thread with the middle of the bottom book and add books on top to provide more weight (tension) then you put the spool into a coffee cup so it doesn't unravel and get out of control as you wind the guides on.
Once you start the thread wrap the faster you rotate the rod blank then nicer the wraps will lay down. I always wrap so the thread is on a slight angle away from the blank. Kind of hard to explain. Instead of the thread coming off perpendicular to the blank it is on an angle. That is how I did it maybe you will develop your own tricks.
Like I said if you have any questions you can send me a PM and I will try an answer it for you. I strongly recommend you getting a rod building book like this little paperback by Flex-Coat "Start to Finish Fly Rod Building".