Doubts have been raised over whether Roy Hodgson's side can actually make the knockout stage and Barkley thinks their first result could be crucial.
"It's very important when you go into a tournament, to set the tone in the first game," he said.
"You have got to start with a good result, go into the game prepared and looking to win the game.
"With all the big-name players it's going to be a big test playing against Uruguay but if we get a good result against Italy we can take confidence into the second game.
"We need to be positive throughout the group stage."
Barkley is one of the more inexperienced players in the squad, having only made his senior debut last September, but feels comfortable with the company he is now keeping and intends to make the most of his first World Cup.
"That is what I dream about, playing against the best players in the world," he told evertontv.
"It's every kid's dream to be doing things like that and hopefully I will get the chance.
"I feel ready for anything. It is football, it is not life or death.
"You have to go on the pitch and get a result and focus on what you have to do on the pitch and not get distracted.
"The top players produce it week in, week out and they are out there every week giving the same performances, if not scoring then setting goals up, always fighting and getting results.
"I will learn a lot. I went to the World Cup with the Under-20s last summer and I learned a lot there - about the (tournament) environment, playing against the big countries.
"I've never been to South America, (I will learn about) the temperatures, preparing for games, being away from home; it will be a good learning curve for me and a great experience.
"After every tournament I feel I have learned something and I come back wanting to progress."
- Sports & Recreation