Lukaku signed for Everton on deadline day from Chelsea and has established himself as the Martinez's first-choice striker at Goodison Park, scoring four goals in four appearances.
The 20-year-old Belgian is no stranger Premier League goals having found the net regularly at West Brom last season - including a second half hat-trick against Manchester United on the final day.
|14/1||Romelu Lukaku is 14/1 with William Hill to be the Premier League's top scorer
"Romelu can be as good as he wants to be," Martinez told reporters. "He will get the opportunity here. He will have the time to experiment things and try things.
"Remember that he hasn't played many 90 minutes in his career and it is important he does play 90 minutes for us because that allows his game to go into full flow. That is the way he is as a player.
"How many games did he play 90 minutes at West Brom? He was involved in 35 games – how many did he play in [from the start]? Seven.
"So it is like seeing a young man who has now become a proper man with an important role and that's what we want him to have here.
"This is the first time in his career that he is going to take that role so everything is in his hands."