Not exactly a piece of advice but a nice anecdote;
Was building my first FS from a second hand frame and lots of bits that had slowly been upgraded on my hardtail.
Constant criticism from the old man, I wouldn’t do it like that…. ouhhh don’t round that etc.
To be fair the old man has an electrical and engineering background and can put his hand to most things. Anyway to stave off the constant criticism I said “here put this on”, gave him a seat and layback seatpost (how bad can you mess that up right?).
Finished the bike, not a single glitch, quick test ride, something didn’t feel right, seat angle was a mile off…. no it wasn’t he fitted the seat back to front.
He got some abuse for that!