Australia have scored five goals in Postecoglou's four games in charge after he took over as national team boss in October, but they have only managed to hit the back of the net once in their two pre-World Cup friendlies.
Against Croatia in Salvador on Friday, Australia edged possession but managed just three shots with two of them on target.
Croatia looked comfortable defending in their 1-0 win and Sterjovski - a veteran of Australia's World Cup campaign in 2006 - believes the likes of Tommy Oar and Mathew Leckie must take the first option in the final third if they are to break open the defences of Chile, the Netherlands and Spain.
Sterjovski wants them to take advantage of Australia's all-time leading goalscorer Tim Cahill.
"From what I saw, their runs in behind were great, they were getting into some great positions out wide, it's just getting the ball in (to the penalty area)," Sterjovski told PERFORM on Tuesday.
"I think sometimes they wanted to take that extra touch or have an extra pass when it was easier just to control the ball and put it in.
"You know, Timmy was waiting in the middle and a few others. So just keep it a bit simpler, I guess. Not to overdo things."
Australia will begin their Group B campaign against Chile on June 13 in Cuiaba and the focus of the Australian media has been on whether veteran midfielder Mark Bresciano will be fit.
Bresciano is expected to line up as the attacking midfielder in Postecoglou's preferred 4-2-3-1 formation if fit.
Against Croatia, Oar took the position as the 'number 10' and was widely criticised but Sterjovski praised the 22-year-old, even if he considers the Utrecht midfielder to be best utilised on the left wing.
"The beauty of it is, Ange chose a squad with a lot of options in the attacking third with midfielders and strikers," the 35-year-old said.
"So he could tweak the formation to choose the best players for that or, like I said before, I think Tommy did a decent job in there (number 10) even though his best position's out wide but you've also got somebody like Dario Vidosic whose also played at the number 10 when he was back at Adelaide."
Some may see the 1-1 draw with South Africa at the end of May and the loss to Croatia as a reminder of Australia's true position ahead of the World Cup with the Asian Football Confederation (AFC) member ranked 62nd by FIFA, although Sterjovski remained positive.
"We can take a lot of confidence out of that game (against Croatia)," the former Lille, Basel and Central Coast Mariners attacker said.
"I thought the guys performed pretty well, obviously without scoring, but a lot of people were questioning their defence and I thought that was probably the biggest positive out of the game - that we looked pretty compact and we didn't give Croatia too many opportunities to score."
