You look at the run up, the body shape. Getting a strong hand to the ball is important. But you need that bit of luck as well.
Blues triumphed 5-4 on penalties after a hard-fought 0-0 draw, following extra-time.
"As soon as the player comes up to take one, I just look at him and think about what way he is likely to go," reflected Townsend. "Then I don't change my mind. That's it. It has been working recently, so I stick to that.
"You look at the run up, the body shape. Getting a strong hand to the ball is important. But you need that bit of luck as well."
Townsend has carved a reputation as an expert at saving penalties. And when it got down low to his left to keep out William Worthington's attempt as the tie reached sudden death kicks, he sent Blues through to their first Birmingham Senior Cup Final since 2008.
"I have been a runner-up twice now in other competitions and I want to win this one now, definitely," said Townsend.
It was not an easy passage for Richard Beale's side against the Midland Football League outfit and the bobbly Pack Meadow pitch was a real leveller.
"That's what cup games are all about, aren't they?" said Townsend. "We just had to dig in and keep to our game plan. At the beginning, it was not to get frustrating if it wasn't going our way, and go from there.
"Obviously we would have liked to have done better, but we achieved what we needed to do in the end."
Townsend added: "When you play game in this cup you are not going to play on pitches that are flat, that are perfect. So you are going to have to change the way you play and adapt to the surface."
Townsend, for the most part, didn't have too much to do on Tuesday evening. But he was alert to make a fine stop from a fierce Shane Benjamin in extra-time when Coleshill carved out their best opening of the tie.
"They were always going to get chances, because of the amount of pressure they put on. They had nothing to lose, in a way. But the lads did well and we made sure we kept a clean sheet."
Townsend joined Lincoln City on a season's loan in August after impressing for them on loan in the previous campaign. But Blues recalled the 20-year-old in January.
"I think there have been ups and downs, with Lincoln, not playing, for me this season," he said.
"That's what can happen with loans. It's just what their manager wants to do and our manager wants. They might be different things. It's football. I have just got to keep doing what I am doing and work hard."
Blues will meet either West Bromwich Albion or Nuneaton Town in the Birmingham Senior Cup final, on a date and at a venue to be confirmed.