Proper way of using a blow dry brush

I recently bought a blow dry brush and want to know what's the proper way of using it.

The way i use it currently, my hair gets flat instantly and they lose the shape that I gave to them using the tool.

My hair type - 2B/2C, dry and frizzy, medium hair porosity. Have used heat tools occasionally, have had keratin treatment done 2 years ago. Right now they are tinted with a burgundy color which is being worn off.

My styling routine -

• Only on hairwash days.
• I dry my hair upto 80-90%
• Apply some serum/heat protectant
• Divide my hair in 4 sections. Go in with the brush and start going through the lengths in the way i want to style it. I do the roots to ends 2-3 times at one time and then hold the curled area with my hands till it cools down (i dont have the curlers so not using them). Heat level is usually low, medium feel high.
• That's it. By the end I finish my last section, my hair seems to get flat.

While my frizz is tamed, the fluffiness and the styling doesn't hold.