I see the bolded phrases every day, multiple times a day on this site. It may be in the title of the question or in the body of the question. Sometimes, it's even in the comments. I feel it is my duty to give a friendly reminder to the community about something that should not be taken lightly in mathematics: Writing.
The following are incorrect:
"How to prove $x$?"
"How to prove $y$?"
If you want to be correct, use the phrase: "How do I prove $x$?" or "How does one prove $y$?"
The forest from the trees:
I remember being in a linear algebra class when a student made a remark to the professor implying that mathematicians don't really need to know how to write, they just need to know how to do math. The professor told him bluntly that he was wrong and lectured us about the importance of writing in mathematics.
In my experience, mathematicians in general are some of the most eloquent people on this planet and their eloquence was not achieved by ignoring the writing process.
I think the best way to tackle this issue is to edit a post that makes this grammatical mistake, and maybe leave a constructive comment. This will sieve out the mistakes over time. I think in the end users will be grateful for this process. I know I'd want to be corrected if I was making a mistake in a language I was trying to learn.
I would like to add, that I am a user that improves and perseveres. My first question on meta got negative eight votes and this one got negative six, but I think I can do even better next time. In general, my progress might be slow. It might take me twice as long, but I will continue to improve.