aforementioned technique is a great tip to know.
insert piston and rings into cylinder FIRST.
then drop cylinder down on studs, and insert gudgeon/wrist pin.
having the rod at TDC helps.
not so critical on the HT, but on an engine with thin rings, ie the oil scraper on a 4 stroke, it saves destroying a cylinder and rings
also helps on multicylinder jobs.
replace the wrist pin clips if you do it this way.
place rag over crank so as not to lose the clip. wear glasses.
ensure rings are lined up with the locking pins in the grooves.
same deal, i do it either way, depending on mood and engine. some engines have the wrist pin pressed into the piston
some are pressed into the con rod and have the bearings in the piston! (mcculloch 10-10 for example)