I'm going to assume you are crimping single pins on single wires, and describe how I do it. If my assumption is wrong, disregard.

My pins arrive with a number of them on a strip. I clamp the strip in a vise (or a visegrip on the table) and bend the one I want to crimp at a 90° angle to the stip. Tangs on the pin should be up, with clearance around the pin for the crimping tool. After stripping about 3 or 4 mm of insulation from the wire, I hold the wire in the pin with my fingers, and put the crimper on the small tangs with the other hand. I crimp them to the bare wire and then move to the long tangs which crimp to the insulation, and squeeze them. Then twist the pin free from the strip.

Then crimp the other pin(s) to the remaining wire(s) and slide them into the plastic plugs, with the correct orientation.

I usually use a visegrip to hold the strip, and sit it on a 2x4 or something, to make clearance for the crimper.

Good luck,
Dave Olson