I first brush out as much dirt and debris as possible.

Then I'll remove the carb ( to be separately cleaned later ) take off the backplate and cylinder head ( carefully noting orientations, etc... ) and wash the engine in warm water.

I'll run water through it repeatedly trying to get out evey little piece of grit and debris.

Then while still in the water I'll gently turn the piston rod, searching for any sensation that there is any grittyness or dirt still in the engine. Usually I'll flush the engine as I do this, just to get everything.

Once done, I'll blow the engine out a bit with compressed air and then flush it with WD-40 to dislodge what water remains.

After that I'll use a bit of glow fuel on the parts and put the engine back together.... minus the carb.

More glow or afterun oil is used in the crankcase ( no glow plug installed ! ).... and I'll then try to turn the engine over gently again checking for any grittyness or debris as I do so.

If it seems OK, I'll move on to the carb.

I tend not to have to dismantle the carb... usually I'll soak it in running water, then blow out all of the nipples with compressed air.
I'll also use compressed air on the needle ports, and check for airflow.

If it seems OK, I'll flush it with WD40, followed by afterun oil or glow fuel....

I'll wipe it with a towel, then re-install it on the engine.

Usually I bench test the engine at this point.... to make sure it is operating properly, using the recommended "break-in" prop size.