If you're the type of person who has to apologize for asking a question (e.g., "This might be a stupid question, but..." or "Sorry if this is obvious, but...") STOP RIGHT THERE. By saying these things, you are perpetuating a culture in which people should feel bad for asking questions or not seeing something "obvious".
Do you want people to judge you when you ask a question? Of course not! Then please stop implicitly upholding this culture of judgment that is so ripe in academia. Everyone suffers when people can't ask questions freely and without judgment.
Next time you have a question, don't apologize for it. Don't preface that you are aware it might be a stupid question. Just ask your question and try to understand the answer without all of the extra bells and whistles of judgment. Please and thank you.