When I first started, the worst thing I was told was that I needed to use a powder that gave the highest velocity when filled to the top of the case mouth. He said that that was where I'd get my best accuracy, also explaining to me about how the more the powder was compressed, the more consistent ignition, and velocity would be. He was also one of the people who says to just scoop the case through the powder, and scrape it off even.
Thankfully God blessed me with quite a bit more sense than to listen to him...