This is mostly for those who are just starting photography or have recently purchased their first DSLR. What are you having the most trouble "getting right"?
For me when I was a kid and starting with photography, I was so confused about f-stops. It took me a while to remember f2 was "bigger" than f22 :^)
When I switched to digital I fumbled with fully understanding how white balance worked. Now every new camera's menu layout loses me. It's frustrating finding and changing menu settings since I use cameras from more than one manufacturer.