How to freeze motion, with and without a flash
Freezing motion is relatively easy... Showing the details of what the eye cannot see in a split second is rather cool, and maybe the most exciting part of capturing moving subjects. I often work with performers so I am used to capturing movement, the idea here is to show you how to get great results by following a few basic rules.
So I assume you are shooting in manual mode!
Basically, there are 2 ways of freezing motion, with your shutter speed or your flash.
1/ When shooting outdoors, with the sun as your main light or in an environment with lots of light, your shutter speed will be the main ingredient to freeze your subject. I usually start at around 1/500s, keep my ISO as low as possible and start at a F-stop around 5.6.
Lynne Karina Hutchinson (London)
5D Mark IV - 35mm f1.4L II 1/500 F5.6 ISO 1000 - 35mm

Injy Pina and Allegra (La cité du vin - Bordeaux)
5D mark III - 24-70mm f2.8L II 1/800 F7.1 ISO 160 - 50mm
Inspiring places, la cité du vin (Bordeaux)

If you are using a flash using the HyperSync or High-Speed Sync mode of your flash to go beyond the 1/200 or 1/250 sync limit... If you don't know what HSS or HS is:
HS and HSS explained :
Hypersync (Broncolor) : https://news.broncolor.swiss/tutorials/hypersync-easily-explained-by-fabio-gloor-part-1/
https://news.broncolor.swiss/tutorials/hypersync-easily-explained-by-fabio-gloor-part-2/
Mohana Rapin (Jardin Botanique de Genève)
5D mark III - 24-70mm f2.8L II 1/500 F6.3 ISO 250 - 24mm

Gillian Leopold (EIlen Roc - Antibes)
5D mark III - 11-24mm f4L 1/2000 F4.5 ISO 500 - 15mm
A Rhythmic Gymnastics photoshoot inside EilenRoc