United have beaten Hearts and Rangers on home turf since McNamara took over from Peter Houston at the turn of the month, after waiting since August to add to victories over Hibernian and Dundee.
Hibs visit Tayside on Sunday and McNamara has urged his players to continue their improvement.
"We have only won three games at home in the league this season," he said.
"With what we have we should be winning more games. Hopefully we can do that and make it a fortress because it's a great place to play."
Former Partick manager McNamara has first-hand experience of the fixture this season and knows Pat Fenlon's Hibs will pose a difficult side to break down.
"I actually went to the game at Easter Road when Hibs won 2-1 against us," he said.
"I thought United were excellent that day.
"They caused them a lot of problems in the second half and had chances but couldn't get the goal.
"But Hibs were very solid. They are a different outfit to the team of last year.
"Pat has assembled a different structure to his team and they have a better defensive record than last year.
"So we know we have to be patient but if we do what we can do, defend well as a team, play well as a team, then we can hurt anybody."