It really depends on how you do it. I am only speaking from personal experience, as I tend to receive mails like that a couple of times a month or more. This is due to me implementing my academic work into software, which people can then use to make calculations.
If you just imagine the person you are writing giving the rant below, and then ask your question accordingly, you will be fine.
I can immediately tell if you made an effort understanding it. Please do so before you write me. While I will surely answer your question, I can certainly have more fun than trying to paraphrase one of my papers in an email.
Ask genuine questions, don't try to hide anything out of fear that I will steal your idea. I wont, I have enough to do. I all too often have to drag out of people what they are actually trying to accomplish, enabling me to give them better answers.
If you are a student, ask your supervisor first. While I will be happy to help, I don't run a correspondence course.
For God's sake: spell check. Your English does not have to be perfect - mine certainly isn't - but I need to be able to understand your mail before answering it.
Don't open simultaneous, parallel mail threads with both me and my co-author. We do not often discuss "help" mail, and if we do, it's for giggles in the coffee room. We will not know that you reached out to both of us, and when we find out we will be annoyed.