In an eve-of-conference article, Carwyn Jones said Welsh Labour won the 2016 assembly election by "fronting up" to people's concerns.
He said the party had "not really addressed" the key economic issues in the 2015 general election campaign.
A "community-rooted" response could reconnect with voters, he added.
Writing on the Labour List website, Mr Jones explained how he responded to the general election defeat to ensure the party recovered in time to keep power in Cardiff Bay.
Speaking of how he was "ripped into" at a Labour public consultation event in Gower, which the Tories had won for the first time in a century, he said the "heated contributions" from the floor had been "hard, but necessary".
"We wanted a no-holds barred assessment of what people thought about politics, and about Labour - and we were getting it," he said.
Mr Jones said "ambitious but simple" assembly election pledges had been developed by having "meaningful" conversations with voters, "turning their concerns into visible action and plans for the future".
Labour won 29 of the assembly's 60 seats, and has kept power by agreeing to consult Plaid Cymru on a range of issues.
However, the first minister said surges in support for Plaid and UKIP in the south Wales valleys showed the need for a "new, different and community-rooted response from our local parties".
Mr Jones said such politics was not "quintessentially Welsh", but "quintessentially Labour".
"In London, Sadiq Khan's superb campaign [in the mayoral election] also showed that Labour can win, right now in 2016, when the politicians give our organisers and volunteers the things they need," he wrote.
"Clear messaging, strong leadership, and a willingness to reach out to the public, even when they've got hard things to say back to us."
Labour can win elections with clear messages, strong leadership, and by listening to the "hard things" voters say, the first minister has said.