They scraped past Scotland by a single point and will have to show greater resolve and better execution if they are to defeat Ireland on Tuesday at Lydney and England at Cheltenham on Friday.
Although they won lots of possession from the scrums where Porthcawl CS prop Ryan Bevington was outstanding and at the line-out through Coleg Sir Gar lock Haydn Pugh, Wales could not finish off a number of try scoring chances.
They should have pulled clear at 21-13 but a fine Scottish try from wing Michael McNaughton seven minutes from time had Welsh nerves jangling by the end.
"We should have sewn it up after the break but we rushed our options too often in prime positions "said Assistant Team Manager Ron Shottle. "We also need to mix our running and kicking game more but all in all it was a positive start from the squad against a bigger than average Scottish side."
Wales had the boost of a second minute try under the posts by Brynteg CS flanker Lee Sims, converted by full back Leigh Halfpenny (Swansea College) and although Scotland answered with a penalty from centre Steven McColl, Wales responded well with a cleverly worked try by the sharp as a razor Halfpenny.
The Scots were always ready to move the ball and were rewarded by a converted try from centre Paul Loudon to come back to 12-10 at the break. With scrum-half Gareth Williams (Colston's) using possession well and wing James Egan (Whitchurch HS) running strongly Wales forced Scotland into errors.
The composed Halfpenny kicked three penalties to one by McColl to suggest that the game was won at 21-13 but the Scots fitness served up a grandstand finish in which wing Mike McNaughton raced in for a thrilling try, converted from the touchline by McColl.
Defence was the order of the day for Wales in the closing seven minutes with flanker and captain Jevon Groves (Y Pant Comprehensive School) leading by example.
In the other game in Cheltenham, England came from 15-6 down to beat Ireland 26-15.
Leigh Halfpenny; James Egan, Jason Tovey, Nick Harwood (Rhys Williams), Gruff Jones; James Thomas, Gareth Williams, Phil Price (Ryan Bevington), Ricky Guest, Patrick Palmer (Scott Andrews), Josh Williams (Karl Maiden), Haydn Pugh, Jevon Groves (captain), Lee Sims (N Cudd), Sam Warburton (H Molitika)
Tries: L Sims, L Halfpenny
Con: L Halfpenny
Pens: L Halfpenny (3)
Tries: P Loudon, M McNaughton
Cons: S McColl (2)
Pens S McColl (2)
Four Home Nations Results: Matchday 01
England 26 Ireland 15
Wales 21 Scotland 20