I've loved words and books and reading for as long as I can remember. When I was a kid, I had a reputation for always having a book in my hand, and that's still true, even if that book is sometimes on my phone's Kindle app. As I grew older and realized there were people behind books, I wanted to write them too.
I studied to be a secondary education English teacher in college, but after graduation, instead of going to work within the American education system as those around me had expected, I went off to Japan to teach English as a foreign language.
I often get messages from non-native English speakers apologizing for their English ability, and believe me when I say, you don't need to do that, no matter how good or bad you think you are. In my experience, non-native speakers always believe their English is worse than it actually is. As someone who teaches English to non-native speakers at various levels every day, I promise I'm not about to start ridiculing you no matter what you're ability is.
As for what to expect from me as a beta reader (whether you're a native or non-native speaker), there are three approaches to beta reading in my view: There's reading to correct grammar only. There's reading to provide advice on how I, personally, believe the story could be better. And there's reading for both. I'm willing to do any of the three. When you ask me to be your beta reader, please let me know what approach you'd like me to take with your story. If you don't, I'm going to ask before I agree to beta for you.
Also, if there's something specific you want me to look at because you're struggling with it or feel like it's a weak point with you're writing, let me know. If you want me to look at both grammar and story, I'd appreciate getting to read the chapter, provide feedback, you make any changes you feel necessary, and then I can re-read for grammar.
Something I can't say enough: Please, please, look over your story a few times for the blatant errors before you send it to me. I can't tell you how often I get stories with tons and tons of typos that the writer's spellcheck should have noticed. I'm not asking for it to be perfect. If it was, I wouldn't be needed. But I don't want my job to become right clicking on misspelled words that are clearly underlined in red.
If English isn't your first language, let me know as well. As mentioned above, I have experience working with non-native speakers in English as a teacher and as a beta reader. It won't affect whether or not I beta for you, but it does change how I will approach the process. One example of how I might approach it differently: When I find something worded awkwardly in a native speaker's story, I may just point it out and expect them to get why it sounds awkward (depending on the situation), but if the writer isn't a native speaker, I get that the awkwardness may not be inherent to you and I'll need to include more of an explanation.
When I beta read, I highlight each change I make in the document so that the writer can see it. I do this for two reasons: 1. I want whether or not the change stays in the story to be the author's final decision. 2. I've found that writers make a handful of mistakes over and over again. Everyone. I don't think I've ever worked with a writer (and I'm including myself in that) who doesn't have a mistake or two that continuously appears. My hope is that, if I highlight the mistakes for the writer to go over themselves, they'll realize what their repeated mistakes are so that they can be aware of it in the future.
As I do have a full plate outside of the world of fanfiction, there will undoubtedly be times when I'm so busy that it interferes with my availability as a beta. I will answer any messages you send me as quickly as I am able to, and if you send me a chapter that I think will take longer than usual to get back to you, I will be upfront with you about it.