You should be aware that there are many English accents. England has, at least, 40 and the US has regional accents with subaccents and has, at least, that many as well. There are Australian accents, South African accents, and accents all over the English speaking world.
Listeners respond to those accents Some have higher status than others. Some accents are associated with regions that are economically disadvantage, some are associated with being educated, some seem “stuck up,” some “cool,” and most of the judgements are made almost instantly at an unconscious level.
It would be nice if it could all be laid out in a spreadsheet, and use it to decide which one is optimal, but an accent that might seem stuffy to one person might seem familiar to another. A “cool” accent might sound childish in the wrong context. Native speakers are adapt at subtly shifting their accents and word usage in different social situations, changing formality, jargon, and even the sounds and rhythm of their speech.
For instance, in the US speaker with Southern accents (of which there are many) are often considered less intelligent. This assessment is instant and subconscious. Many people from the South have learned to lose their Southern accent and adopt an accent closer to what is called, General American English, an accent that doesn’t really exist, but is a group of accents that are so similar they are for a non expert to tell apart. They are spoken by educated people and in many urban areas, especially on the West Coast. These are the accents that are used as default in movies, television shows, radio, and other media. Since they are associated with educated, economically better off, or famous people, they confer some status.
I have friends from the South whom I had no idea had Southern accents until we went out for a few drinks and they let down their guard. They had adopted the higher status General American English accent. It is likely that when they go back home to their families and the people with whom they grew up, they will prefer the accent that is used in that area. It sends an unconscious signal “you’re one of us” and were they to use General American English it is likely that they would be perceived as rejecting where the they came from. They might be perceived as being “snooty” and “too good for their own kind.” [i] In other words, an accent can identify you as a member of an in-group.
[i] For a detailed look at this experience, I recommend the book Hillbilly Elegy, by J.D. Vance.
So, when you are trying to learn to have an American English accent, which accent should you choose? How can you choose it?
I am going to make it simple. I am going to teach you my dialect and accent.
I have an accent that is California English. It is similar to General American English with a few minor differences. Even more specifically, I grew up in different places in California, but mostly in Northern California and I have lived in Northern California most of my life so, to the extent that there is such a thing, I have a Northern California Accent. (Even within a seemingly similar geography, there are slang expressions used by Northern California youth that are looked on with contempt by Southern California youth.)
Throughout my life, I have often been surprised when after a short conversation about nothing important, the weather, for instance, people remark, “you are, obviously, very intelligent.” I would be baffled how they came to that conclusion. As I learned about language and linguistics, I realized that my particular dialect was one that gives that impression.
I have taught classes in a variety of subject. I have taught technical subjects like programming languages, Unix/Linux internals and device drivers, Social Network Analysis, binguistics, English as a Foreign Language, business, and Information Systems. My students have been from many countries and they have often remarked that they find my English easy to understand.
One reason for this is that my dialect and accent is close to the one they hear in movies and other media, one of the main places where they learned English.
There are many dialects and accents you can learn, but it is useful for you to learn one that gives people the impression that your are intelligent and is easy to understand by people of many different nationalities, so my accent/dialect is a reasonable one for you to learn. This has the added benefits that I can provide audio (and video) and easily modify it and if you take a live class from me, you will be familiar with my voice and pronounciation.