Jonathan Thomas concedes Wales' Six Nations hopes have been ruined by "naïvety" and insists Warren Gatland's men need to play "conservative" rugby.
Wales have started slowly in each of their three Championship clashes to hand their opposition commanding leads.
The Welsh fought back to beat Scotland after England heartbreak and ahead of Friday's home loss to France.
"Perhaps we're a little naïve and in the first-half of games we have to be a little more conservative," said Thomas.
Wales have been architects of their own downfall in this Six Nations, the 2008 Grand Slam winners giving the ruthless French two interception tries as the visitors raced into a 20-0 interval lead in Cardiff.
Alexis Palisson and Francois Trinh-Duc benefited from misplaced passes from James Hook and Shane Williams as France took control at the Millennium Stadium - before Wales fought back in the second half to lose 26-20.
As a side we've got big intent to play, we want to entertain people, we know we have good skills and as players we want to show everybody how good we are
Wales forward Jonathan Thomas
Wales played catch-up in their Six Nations opener at Twickenham as they allowed England to build a 20-3 lead before coming back bravely to be within three points of the English with eight minutes remaining.
But James Haskell's converted try - after Stephen Jones' pass had been intercepted - sealed England's win.
Then Scotland led 18-6 in Cardiff before Wales dramatically won the game 31-24 in stoppage time after scoring 17 points in the final three minutes before the Grand Slam-chasing French made the hosts pay for their careless rugby.
Fly-half Stephen Jones maintains Wales are "not far off being a very good side" and the British and Irish Lions star believes their high risk, high reward 'Welsh way' of throw-the-ball-about rugby is "the way we want to play the game".
But experienced forward Thomas has urged Gatland's team to be more cautious against Ireland at Croke Park on 13 March.
"We're not starting the game in the manner that we should," the Ospreys forward told Scrum V.
"We must make sure we're error free as we are guilty of playing a bit too much in our own half and giving away far too many interception tries.
"As a side we've got big intent to play, we want to entertain people, we know we have good skills and as players we want to show everybody how good we are.
"But France had a massive kicking game, they came and kicked and relied on our errors - and it worked.
"We have confidence in our ability and can make line-breaks against any side in the world.
Extended highlights - Wales 20-26 France
"But the defeat shows, if you make silly errors against sides like France and give them a 20-point head-start it is very difficult to come back from.
"It is three games on the bounce that we have conceded tries in the first-half.
"It shows we can't give sides a start in the first-half and leave us to always rely on our rugby ability to get us back in the game in the second-half.
"Now we have to sit down as a group and come up with some solutions because it is not good enough as at international level you can't make mistakes as you get really exposed at this level.
"We were bitterly disappointed and frustrated after the game because when we play as well as we did in the second-half and France were physically out on their feet, to come away with a loss is really disappointing.
"We're confident in our fitness and the last couple of weeks have shown that we one of the fittest teams in the world with the intensity and the way we finish games.
"We have shown some incredible fitness to play the way we have in the second half of games. But it was our crucial errors which has killed us."
Wales outscored Championship favourites France 20 points to six in the second-half in Cardiff.
And Thomas, who will win his 54th cap in Dublin on Saturday week, insists the Welsh can beat Triple Crown-chasing Ireland, last year's Grand Slam champions, if Wales learn to keep it tight in the first-half.
"As a team we don't fear playing anyone at the moment," said the 27-year-old, who made his Wales debut in Australia in 2003.
"A lot of sides wouldn't relish playing us but we must cut out errors and up our concentration, particularly in the first-half.
"And if we can go into second-half against Ireland level, we'd back ourselves against anybody so we have to focus on upping our concentration levels and being more efficient."
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