Hey Roy, I am a new builder too, working on the tail kit. I feel your pain brother! I have messed up some aluminum parts from not paying attention to their orientation, maybe because I was tired at the time.
Here's some suggestions that may help.
1. Cleco'ing and assembling parts is non-destructive. Do this part and then double check everything is lining up, and matching up with the plans. Its fun and doesn't ruin parts.
2. Before doing any "destructive" work (like drilling, cutting, or riveting), I will cleco the parts together, and COMPLETELY look over the section and match it up with the plans, and even measure a few spots to make sure I have it assembled correctly. Even though the plans are not drawn at scale in many spots, the number of rivet holes their orientation and part layout are spot on. Tooling holes are also shown on the plans, so align them on your parts with the plans as well. They can make finding orientation really simple.
3. Read the plans and study the work before even going into your shop. Try to visualize what will need to be done and how it fits together and why.
You'll get better as you build, and with experience you end up making better and better "product" as your output. It sucks the first few pieces you build, but you do learn and get better as your skill increases.
Stay with it man! You'll be making high quality work in no time.