The League 2 side, who haven’t faced LTHV since being promoted from the Lowland League, will be in unfamiliar territory at Ainslie Park this weekend when they occupy the away dressing-room for the third-round clash as the sixth-tier club also uses the Pilton venue as their home ground.
City's form has improved in recent weeks having taken seven points from their last three fixtures, but Naysmith revealed he has done his due diligence on the East of Scotland Premier Division club.
"This is Lothian Thistle's cup final," he said. "I went and watched their replay (against Edinburgh University) and we had a scout watch them last week. We've got other video footage and other reports so we've done everything we can as staff to prepare the players properly.
"Obviously the players don't know a lot about them but it's been up to us to educate them on the opposition. We need to go out and put in a professional performance. But it won't be easy as it's their cup final."
City played out a 1-1 draw at Elgin on Tuesday night and Naysmith added: "You can become greedy but I don't think we deserved any more than a point.
"We can play better, pass the ball better and create more chances. We've had two tough away games at Stirling and Elgin but tomorrow is a massive game for the club and one we won't be taking lightly."