Tanner guided the Terrors to 11th in Ryman Division One South, and it was enough to convince chairman Steve Adkins to keep the 28-year-old at Imperial Fields for a second season.
After taking the reins just two weeks before last season, Tanner admitted the past year has been a huge learning curve.
The former Sutton United and Hampton & Richmond Borough favourite endured a tough start to management, but a series of turning points meant the season ended on a positive note.
“It’s been tough, especially when you think we picked up only two points from the first five games and that I’d taken over so late in the summer,” he said.
“We did nothing in the FA Cup or Trophy, and so there were times in those early days when I wondered if I had made a mistake.
“But Adam Moriarty [assistant coach] and I have learned so much so quickly, that to finish in mid-table was a real achievement.”
He added: “We are really looking forward to having the time this summer to work on the team, hit the ground running next season, where a place in the play-offs has to be a priority.”
Something Tanner learned quickly was man-management, and he had to change his style and grow a hard skin when it came to letting players down.
He said: “My relationship with the players has changed. We used to have open discussions in the dressing room, but that turned into an open court where sometimes too much was being said.
“We stopped that because it was unhealthy to the team ethic.”
He added: “I never really enjoyed telling players they had been dropped. When we dropped Jordan [Cheadle] because he was off form, he was unhappy, but when he came back he was a much better player for it, so we knew we were making the right decisions.”
Tanner believes the departure of Frankie Sawyer in January was key to a change in formation that led to a run of just four defeats in 17 games in the second half of the season, while big wins over Whitstable Town and Walton Casuals convinced him his team could play.
However, from a personal point of view there is another reason why Tanner is confident of future success.
“You want to do your best as a manager and do everything you can to stay in a job,” he said.
“Being asked to stay here next year means we have cleared that first hurdle, and now it is all about next season.”