Looks like you are doing good. I clean the cases with a mix of anti-bac-wet-wipes, alcohol + q-tips if needed. Toothbrush + alcohol sorts the grilles.
For the PCB, take it outside and gently brush with a soft toothbrush or old paintbrush. That dry dust will come straight off.
It's only tricky when there's grimy oily black residue to remove from PCBs. Then you really have to go to town with everything in the cleaning kit.