Here's one I crimped earlier
1. Twist wire with thermistor strand
2. Fold to size of crimp
3. Push crimp over, then press together with pliers (or crimping tool if you have one)
How do you actually insert the thermistor? It looks like those two leads will short the instant the extruder head moves at all.
I actually wrap each lead in Kapton tape before attaching it to the nozzle with more Kapton tape. Generally this is secure enough to handle the movement of the head.