I'm micman60, a long-time member of this site who's struggled through writing good and bad fanfiction. I'm not an expert - I'm just a dude who likes reading fanfic - but I like to think I have a decent idea of what makes a good story. I'd like to help someone who needs feedback on their work.
To be honest, I've never beta'd anyone else's story before. But if I were to beta a story, this is how I'd do it:
* First, I'd give it a read-through to see how the story flows and to spot any spelling/grammar errors. After that initial read-through, I'd begin writing a report of your story, beginning with my general thoughts and listing any spelling/grammar errors.
* I'd look back on any potentially wonky bits of your chapter - pieces of story that don't flow very well in the whole of the chapter. After getting the general idea of what you were trying to convey, I'd offer a few general suggestions on how to edit the segment so that it flows smoother.
* After completing the report, I would send it to you and wait for your response.
It's important to note that I'm not going to be an absolute dictator about how your story flows. Spelling and grammar mistakes are one thing - I'll strongly recommend fixing them up, or running the chapter through Microsoft Word or somewhere else with spellcheck. But if I do see a point where the story might snag a little and feel out of place, that could just be me overthinking things. If I offer suggestions to make the segment flow better, I don't expect you to follow every word out of my mouth blindly - check the parts I mention and see how you feel about them, and if you feel the same way, try and rework the segment in your own way. I am a guide first and foremost - your story is in your own hands to shape and mold, I'm just a preview audience who can give you a new perspective on your work and help you catch some sneaky errors that slipped away from you.
My expectations for anyone seeking my help:
* Please be fluent in English. I'm sorry if that's rude, but I'm not a big fan of writing that reads like it's been translated from one language to another. That isn't to say that I won't beta for non-native English speakers - I know people who are very fluent in English who have it as a second language. Just please have a decent grip on the language - if you're not sure if your writing meets my standards, message me anyway and I'll tell you what I think.
* I'm not a fan of straight-up smut. In layman's terms, I don't crap where I eat - smut and porn are one thing, story and plot are another. There are very few exceptions to this. If you want me to read an M-rated lemon, at least focus on the romantic aspect of the relationship. If you're writing a T-rated harem comedy full of sexual hijinks and the like, count me out - I will not beta it.
* Finally - and this is a big one - I would love to beta for someone who practices critical thinking. As an author, I don't expect you to accept every word I say as absolute law, and I don't want to deal with someone who gets hard-up and defensive to every criticism I may offer. Like I said - I'm not an authority figure, I'm a guide. I make suggestions, provide some points to think about to possibly make your story better and point out spelling errors. I expect you to be into your story, and know what you want to get out of your story. Work with me, let me know if I'm misinterpreting your story. I want to help you, but that doesn't mean I'm here to smother you. Please, have your own standards and don't be afraid to make your own decisions.
I hope you consider me as a potential beta reader.