Firth has seen his handicap dip from 3.3 on June 1 to plus 2 by the time he finished second to club-mate Phil Tomkinson in the Yorkshire Order of Merit.
He won twice this season – at York and Seaton Carew – and was the only player within touching distance of Tomkinson going into the Order of Merit’s final event, the Moortown Masters.
“I needed to win and for Phil to finish seventh or worse,” said Firth, who finished runner-up to Howley Hall’s Ben Hutchinson while Tomkinson placed sixth.
“I’m not too fussed (at missing out) because Phil deserved it in the end.”
Firth puts his leap forward this season down to working with performance coach Duncan McCarthy, of Ignite Sports – a fellow Moortown member – and golf coach Dan Seaman, of Leeds Golf Centre.
“Duncan does all my scheduling, and helps me mentally and with the performance side of my game, while Dan deals with the technical side of my swing,” he said.
“I started with Duncan off the course in January and have been working with Dan since October last year.
“It is through a combination of working with them that my game has improved.”
The 19-year-old says one of his biggest problems was an ineffectual practice regime, which McCarthy has dealt with.
“ I was going down the range and practising for five hours, but I would come back and I hadn’t learned anything,” he said.
“I have reduced my practice time this year, but it’s more specific on a daily basis – it is all planned out.
“My routine now covers every aspect of my game, I’m not just going down and doing the same things every time.”
The improved mental side of his game proved beneficial going into the Moortown Masters finale.
“I think I missed five greens (in regulation) over two rounds, which isn’t bad round Moortown,” he said.
“Phil struggled for a bit of it and I thought ‘if I keep going I can do something here’, but he just hung on.
“Even if I’d won he would have beaten me by six points still for the Order of Merit.”
Firth made it in as a last-minute reserve in the English amateur championship and progressing to the match play stages meant he could not compete in the Cobble Hall Scratch, which Tomkinson won.
“He won at Cobble Hall when the English amateur was on, but I learned so much from it that I don’t really mind,” said Firth, who has been invited to train with Yorkshire’s county coaching team during the winter.
“I would say my ultimate aim is to be a touring professional, but I’ll stay an amateur for the next couple of years and play more national stuff.
“At the start of year I started studying (to become a PGA assistant professional), but now I’ve decided to leave that a couple of years to concentrate on playing.
“Since I’ve been working with Dan and Duncs I’ve come down rapidly this year so I’m going to do national stuff instead. I wasn’t low enough before.
“At the English I was 75th reserve and I got in, off 1.1, at seven o’clock in the morning – and I was on the tee at eight.”
He is looking forward to joining the Yorkshire coaching system, which will focus on the short game.
He hopes to build on the work he has done in this area with McCarthy.
“With Duncan’s help I’ve got distances all charted out and I’ve got clubs for every single yardage, so I don’t have to think about it when I set up to the ball,” he said.