Carry how you feel comfortable. The HK45C can be carried...
Cocked and locked (hammer back, SA, safety on)
Decocked (hammer down, DA, safety off)
Decocked and locked (hammer down, DA, safety on)
In addition, once you find one method that works for you and decide you want to keep it that way you can swap the detent plate to remove the function that you don't use. For instance, if you choose to go C&L it can be converted to V9 which will remove decocking function of the control lever.
I carry my USP's in V1 decocked with the safety off. This means draw and depress trigger to fire. My reason for doing so is it becomes the same approach as the Glocks I usually carry.
"Don't hit at all if it is honorably possible to avoid hitting; but never hit soft." ~ Theodore Roosevelt