1 - no distractions at the bench people or otherwise
2 - one powder, one primer and one caliber on a time on the bench at any given time.
3 - Write up you reloading procedure accounting for every single task you make to load a round and print it post it next to bench as a ongoing reminder especially if you have periods of time between loading. Build consistent reloading process.
4 - check your scale constantly with calibration weights to insure good consistent weights.
5 - Manuals are there to prevent you from harming yourself. The loads are MAX and are not lawyer loads. Use a manual for load data and not something you took off the internet unless you have the confidence and knowledge to work a load up on your own.
6 - NEVER start a any MAX load under any conditions whatsoever. ALWAYS work your loads up for your rifle gradually. Different powders, brass, primers and bullets (even different lots) can cause instant pressure problems.
7 - Stay off the lands with your loads until you have the equipment to measure accurately and the knowledge to understand pressure.
8 - A stiff bolt is not the only pressure sign to be aware of and stop shooting immediately until you have resolved the pressure signs.
9 - Temperature has a huge impact on load pressure so a load that is fine in January may be serious pressure problem in July.
10 - record every single load you make. Use a marking system to differentiate the loads in each lot that you are testing. I've used different color Sharpies on the primers or bullets to color code each load step. One of the positive aspects of tracking loads is you know the barrel count as well.
11 - get a really good bullet puller. You will make mistakes and will want to save the load as much as possible. I have saved a lot of components with RCBS puller.
12 - 2x on the floor mat. It also traps dropped primers etc and keeps them from rolling around.
13 - I was over sizing my brass for quite a while until I bought the tools to show me how to properly headspace my brass. I wasted a lot of brass!
14 - I switched from measuring the COAL to the tip of the bullet to measuring the ogive OAL when I bought the headspace tools years ago and they really teach a lot more about consistent reloading.
Reloading is like a really good pie recipe. You have to use good components, measure accurately, and have a reloading recipe that has repeatable accuracy. You really have to track and record your data so when you look back at a load, you can legitimately decipher what you did and can repeat it. Just like the pie, why did it taste so good?
I have more mistakes that I've made over 40+ years of reloading to share but I've done enough scare even myself.
Muddy