I'm trying all kinds of options to make sharp edges and rounded corners for an excavator arm. Apart from just using bevel, I also have tried to use "make sharp" and "edge crease", but it doesn't look nice. Any suggestion have I can improve my model with more edges and where to put them or any other approach to make rounded corners with sharp edges?
If you're modeling using subdivision, at its simplest, this sort of topology will give you a rounded corner: supporting loops close to the sharp edges, and looser on the round corner. You have a degree of control over the tightness of the corner by sliding the edges on either side of it.
However, if, for example, you you wanted a perfect circular arc in the corner, breaking instantly to perfectly orthogonal edges, you might choose a bevel, as suggested by atek.