Central defenders Anthony Charles, a recent signing from Northampton, and Guy Branston were in top form for Argyle, whose on-loan Ipswich striker Ronan Murray hit the crossbar in the 33rd minute.
The hosts had the better opportunities to score with on-loan Yeovil striker Reuben Reid's downward header cleared off the line by Daggers defender Femi Ilesanmi at the start of the second half.
The Londoners were limited to long range efforts although home goalkeeper Jake Cole made a superb save to keep out Luke Howell's deflected, rising shot in the 18th minute.
"I think we have played better there than the previous two and I never felt we were going to lose the game because we were solid," said Sheridan, who remains unbeaten as Plymouth manager with a win and two draws since taking charge.
"We should have won the game with the chances we have had - one off the bar, another off the line and at the end when Matt Lecointe has hit the target.
"That's two clean sheets on the spin now, five points from three unbeaten games and something to build on. I would have preferred seven points and if we had won we would have jumped three places up the table, but we have still got ourselves out of the bottom two and that's the important thing."
Sheridan added: "It got a bit scrappy towards the end but I didn't feel we were in danger. They are a good, organised side and I know John (Still) and his set plays are strong and they have got some big lads in the team. But I thought we defended well again and I don't think our keeper has had much to do.
"We all know the importance of winning the game and we were all getting a bit stressed on the sidelines and you can see the lads getting a bit edgy because we all want to win the game.
"We have got to take the clean sheet and now we are three unbeaten, so we build on it."
