Frustrated with inability to do body work!

Spent some time hopefully completing the fenders to the point I should start spraying primer builder and blocking it down. Its not perfect but I think I will be happy with it. This body work stuff is tuff work!
Now i'm starting the doors. Same thing on the skins, I had to weld the trim holes shut.
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Once that was done I took the grinder and ground down to surface. Then I took some filler and spend across the door so I could see where I stood as for high spots and low spots. Here is where I am at after sanding off the filler with a 11" block and using 80 grit paper. As you can see each spot I welded appears to be lower than the door skin so hopefully I wont have any high spots.
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Now the question is how should I attack this so I get a nice smooth skin. This will be the same thing I will encounter on the rear quarters when I get to them. The front fender wasnt quite this way as it had more curves that hid any uneven surfaces.
Looking for some good advice so as I go forward i'm not wasting time reworking my work!
Thanks
Rod