Tony has converted me to Lee dies. I got the deluxe .40 kit. I use a Redding Competition Seating Die which is f**king marvelous. I prefer to sort my brass my brand, some guys don't, but I'm just picky. It helps me enough in my process to justify the effort.
Make sure your powder measure is dialed in. I cycle mine 30-40 times and get the meter that I want before I charge cases, but im kinda picky.
I check my seating depth frequently. Every 100 rds and I verify my powder charge and crimp, as well.
It's not rocket science. The trick is doing it consistently and going about it the same way every time. Developing a safe and efficient method and sticking to it.
Be very careful when loading at or near maximum charge weights. Stay safe! ...or you won't be having any fun.
When setting up your Dillon's, don't some of you guys put cases in each station to balance the tool head as you calibrate the dies?