mark a centerline in both directions (+) and make your measurements from there. it's easier to measure and get the same point from a line than it is on a radius.
alternatively, print your entire layout on paper and apply it you your workpiece.
alternatively again, make one good piece ( with screw holes and everything) and use it as a template to create 2 identical parts from it.. if you use a piece of MDF or plyboard, you can easily mirror the parts (left and right sides) by simply flipping the board.
Ideally you want to design your things so that you really don't need to fuss and measure out exact positioning of battens and holes and whatnot. I made my cabinets so I can just simply align the batten on the edge of the piece and staple it on... subsequent parts self align to the edge and can be simply attached.
If I drill a hole, I have a jig. It is designed to self align to an edge and positions my bit where it needs to go. This one shown is also designed to do 2 sides so to do the other side, just flip it around and use the other hole. Mind you, I'm doing more than one cabinet, but in the interest of speed and consistency, I have jigs, templates made up for everything...control pieces I use to align parts so they are centered. All the cabinets come out identical.

