The Welsh Government must be prepared to "back up" its new overseas offices when they open next year, a former UK trade minister has warned.
Lord Digby Jones said an office was "only as good as the input they have and the products they can sell".
Economy Secretary Ken Skates said the government was investing in countries with "huge potential for exports".
But Plaid Cymru AM Adam Price said such a "shop window" for Wales had to display products people wanted to buy.
First Minister Carwyn Jones announced last week that five new offices would open in 2018, bringing the total number of overseas offices to 20.
Paris, Dusseldorf, Berlin, Montreal and Doha have been chosen as the new bases.
"We've strategically picked five new offices in five new locations where we know there's huge potential for further exports," Mr Skates told BBC's Sunday Politics Wales programme.
"Where it's absolutely essential that we build networks and relations and where we give business access to decision-makers".
Lord Jones, a former CBI director general who served as trade minister under Gordon Brown from 2007 to 2008, told the programme he was "hopeful" the increased overseas presence would pay off.
But he warned: "When there's an office, some people back at the ranch will stop trying because they'll think it's being done by the office. You couldn't be more wrong.
"The office is a good catalyst - it's a good route, but it can't do it on its own."
The Welsh Government would need to ensure it "backs up" the offices with regular visits from high-ranking politicians, Lord Jones added.
Mr Price, Plaid Cymru's spokesman on finance, business and the economy, said: "I don't think just having boots on the ground is sufficient.
"What you need is, yes, a physical presence, but you also need a strategy which is very clear where the opportunities are - and that's what we don't have."
Questions have been raised about the performance of the Welsh Government's existing overseas offices.
The Federation of Small Business has highlighted figures which show exports have fallen to countries where the government already has a presence.
The Welsh Government has disputed the statistics but Mr Skates said new performance indicators would be introduced.
"We need to make sure that anybody who works for Welsh Government abroad is aware of their purpose and is aware of the expectations that Welsh Government has on them," he said.
Julia Brooker is a Cardiff-based artist who has had support from Welsh Government staff working overseas.
Soon after going on her first trade mission in 2004, she secured an order large enough to allow her to give up her day job.
Ms Brooker has since been on many more Welsh Government business trips including several to the far east.
"The main help I get is to go on trade missions," she said.
"But initially it was that market research right at the beginning by somebody actually living in Hong Kong who was contracted by the Welsh Government to be there and find the right people for me to start off.
"That was crucial - my business would have died years ago without their help."