Roy Hodgson's squad are amid an acclimatising training camp in Portugal this week, and have been spotted donning jackets in the heat to further emulate the humidity that will encompass them in South America.
Everton mainstay Baines, who was long denied a permanent spot in the England setup by Ashley Cole, said he cannot afford to assume the left-back role is exclusively his - with Southampton teenager Luke Shaw also in the squad.
"I'm not going to allow myself to think I'm the main man,'" Baines said from Portugal.
"At this level, the competition is always going to be there. You have to keep on your toes and not get complacent because if you don't do the right things then you are not going to be playing.
"Things can change very quickly so I think whoever starts the first game in the tournament has to do the job otherwise they are not going to stay in the team.
"I looked at what might happen and it was obvious three doesn't go into two. The manager could have picked any pairing and no one would have really questioned it.
"But the fact he has chosen me and Luke is a great vote of confidence, especially because Ash is a phenomenal player, a great guy."
Working in Baines' favour is his experience at the 2010 World Cup in South Africa, despite being cut from the final 23-man squad under Fabio Capello - seemingly for a throwaway line.
Baines said a quote about his children back home in England was translated into homesickness, which may have been a contributing factor to Capello's snub of the defender.
"What happened with me four years ago goes to show the way people go mad for the World Cup," Baines said.
"One line, when I talked about my kids, was turned into 'he's homesick'.
"The fact that I went to Euro 2012 and being ready for this one underlines it was very much taken out of context at the time.
"It was a disappointment and set me back but now it's coming and I really want to go and enjoy it."
Baines said he understood careers lived and died on World Cup moments, however, the 29-year-old said he takes everything with a grain of salt.
"Of course I know there are heroes and villains and stuff like that but how you deal with that is down to you as an individual," he said.
"You can't deal with situations like that on the horizon. The important thing is perspective. It's easy to say it's a game but it's more when there are so many people who are emotionally involved."
