A second Scottish independence campaign must learn the lessons of Brexit, SNP members will hear this weekend as a veteran grassroots campaigner calls on supporters to adopt a more conciliatory tone.

Elaine C Smith, chair of the long-running Scottish Independence Convention, told the Guardian: “People need to be reassured that we’re not re-running the 2014 campaign. Some people loved it but some hated it.”

Around 2,500 delegates are gathering in Edinburgh for the SNP’s spring conference, days after Scotland’s first minister, Nicola Sturgeon, said she would introduce legislation to allow the option of holding another independence referendum before 2021 if Brexit goes ahead.

The SNP’s Yes.Scot campaign portal went live immediately after Sturgeon’s statement to Holyrood, and Smith’s non-party campaign Voices for Scotland launched the following day.

“There’s a substantial group of people who want to be convinced but don’t want to be told they were wrong by shouty men,” Smith said. “We need a gathering place somewhere in the middle, to avoid that awful Brexit situation of angry, opposing sides.”

The SNP’s deputy leader and campaign director, Keith Brown, said: “We do need to learn lessons from the Brexit campaign. Perhaps the biggest one was that it split the UK, but with virtually no information. We need to be much clearer. From the start, Brexit was an exclusionary process. The way we conduct the campaign has to be an advert for an independent Scotland.”

Privately, pro-independence campaigners and senior SNP figures agree that the emphasis must now be on “winning well”, reaching upwards of 60% support in order to avoid similar splits. But they are also aware that despite the chaos at Westminster, support for independence has not increased substantially since 2016.

Brown has instituted regular days of action since he took up the role last summer, but said campaigning would now “step up a gear” after Sturgeon’s announcement. “Given all the uncertainty that remains around Brexit, one thing we can effectively do is strengthen support for independence, which will then strengthen our call for a section 30 order when we make it.”

After Sturgeon’s statement on Wednesday, Theresa May’s spokesperson and then her de facto deputy, David Lidington, ruled out the prospect of the UK government granting a section 30 order – which would transfer the necessary powers to hold a referendum to the Scottish parliament – before 2021.

Sturgeon said she would not “spend too much time bothering about the diktats of a government that I expect will be out of office before too long”, adding to speculation that the SNP could demand such a concession from Labour as a price of supporting a minority Corbyn government at Westminster.

Heather Anderson, an organic farmer from the Scottish Borders who first became involved in politics in 2014 and who is now on the SNP’s candidate list for the European elections, said Sturgeon’s statement “releases a lot of energy and optimism. All the people who were fired up before 2014 have not lost that passion, and there is still a real hunger to build the country that we want to live in. So I’m pleased that we can start talking about it again.”

But the immediate focus is to get voters out in next month’s EU elections. “It is almost like a second referendum on the EU,” Anderson said. “A vote for the SNP is a strong message about wanting to remain, and we are saying to people to lend us your vote, even if you won’t vote for independence.”

While the SNP leadership insists support for a second EU referendum can sit alongside support for a second independence referendum, there are still those who fear that this twin-track approach undermines a future independence drive and makes it harder to talk to the substantial minority of independence supporters who also voted to leave the EU.

SNP conference delegates are often characterised as conformist, but the leadership can expect some pushback on its economic plans. A motion to be debated on Saturday afternoon aims to adopt as party policy the post-independence blueprint from the SNP’s sustainable growth commission, which attracted a wave of criticism for what many saw as an overly cautious and market-driven approach, including its plans to keep sterling for an indefinite period while cutting public spending and focusing on deficit reduction.

Patrick Harvie, a co-leader of the Scottish Greens, dismissed the plan at this week’s FMQs as “closer to the failed economics of the UK”, and it now faces a backlash on the conference floor with a number of amendments tabled by MPs and former MPs, trade union groups and local branches.

Jonathan Shafi, a campaigns organiser for the thinktank Common Weal, which has proposed a plan for transitioning to an independent currency from day one of independence, said: “There is strong grassroots feeling that accepting the growth commission recommendations in their entirety is not the direction we should be taking. Independence in name only is not what we are aiming for. We want real social and economic control and transformation.”