1) rotate my shoulders, holding weights with hands. This is already an important warm-up, with the effort distributed on all spine. It improved body posture immediately.
There are other warm-ups, that I will show here with images from the web.
2) Squat warm-up. I do it with weights to ankles and wrists rotating or with chair oscillations.
3) Then with kettlebell. I rotate all the body in a circle.
Find other tips here:
4) push-ups with ankle weights change completely the weight distribution. On the core.