What can go wrong here…..
Crown of thorns slips and quarters the queen. Err… exercise patience and wait for a virgin to hatch mate and lay, or produce wallet/purse and use same to buy a replacement. Or unite with a nuc with a mated queen which you had handy on the sidelines in case of err…. disaster. 😉
I catch the queens by the wing with bare fingers and take it from there. The crown has a nasty trick of suddenly shooting through the midrib and disaster strikes.
The bees ball the queen and kill her. As above. How to avoid? Mark, wait and smoke the queen and the frames you are putting her back between so she smells ok.
The scissors clip her leg too….. she is doomed and it would be kinder to put her down. Then as above again. How to avoid? Practise on drones, and for your own sanity kill them once finished otherwise finding that queen is going to be tricky…..