An important part is the thickness of the crimptool.
If it is thicker that the wire crimp part of the connector it will bite either into the mating part of the connector (which it absolutely should not!) or into the insulation crimp.
The latter is also unwanted as the insulation crimp will be larger in diameter due to the insulation, that would result in a lower quality wire crimp.
Some times it may 'just' fit but still bend the connector.
Some crimptools have two dies in one so that both the wire crimp and the insulation crimp are done in one go.
The connector should be positioned to that the wire crimp and the insulation crimp fir neatly into their part of the die with the mating part well clear of the die.
The point about the thickness applies here too, especially for the wire crimp part.
You can see that one half of the die is wider, the is for the insulation crimp.
The narrower part is for the wire crimp.
The wire would be on this side, the mating part on the other side.
You don't want to punch, touch, bend or push the mating part in any way!
It should stick well out of the tool.
Another point is the thickness of the wire and the die chosen.
If you try to crimp in a die that is too big for the wire the crimp will end up loose or too flattened instead of neatly wrapped around/into the wire.