Wanderers had won just one of their previous seven games but goals from Dave Edwards and Lee Evans breathed fresh life into their bid to make an instant return to the Championship.
Jackett said: "The recent performances have been good but we haven't got the results that we deserved.
"Generally our performance level in the last few games has been better than at any stage this season. But we haven't been ruthless enough up around the box. When you are on top you need to score goals because if you don't you know the opposition will come back at you.
"So I was pleased that we got the goals and got a lot of chances as well - particularly after we went 1-0 up. There are good signs at the top of a very competitive league.
"If you keep playing well it falls for you. We have set some standards when we have been in control of games so it is up to us when we are on top to put sides away. But if you keep playing like that results do come.
"It was a key game and a key result because the pressure builds up the more that you don't win in this game. We understand that.
"You need to score goals when you are on top and I felt that the goals went in at the right time.
"We looked as if we were going to score more goals. Our football has been very good and we have had control of games without having that cutting edge.
"It is something that we have talked about and we have worked on and we know that we need to improve on."
Goalkeeper Wayne Hennessey, who had refused to play in their previous game against Gillingham amid rumours of interest from Crystal Palace, was left on the bench with Aaron McCarey continuing between the posts.
Jackett added: "Aaron did not deserve to be left out. In terms of what happened last week with Wayne that has all been forgotten about. He has come back into the group and was professional and worked hard."
Edwards, who had seen an earlier effort cleared off the line by Jack King, finally made Wolves' pressure pay in the 28th minute when he picked up a neat pass from Kevin McDonald and powered a shot past goalkeeper Declan Rudd at his near post.
Preston, who hit the crossbar through a Joe Garner cross three minutes after Edwards struck, had their fate sealed by Evans after 55 minutes when he made no mistake from close range after Rudd had pushed out a shot from James Henry.
North End had arrived at Molineux on the back of five wins in seven league games and with three in succession. It was their first defeat in nine away league games.