As a blogger or content writer, chances are good that you'll be contacted by readers from time to time. They may have questions about what you've written, or questions about your niche unrelated to your article or post.
You probably try to be as helpful as you can--responding to comments, answering emails, giving advice when asked for it, and just generally trying to help your readers.
But sometimes you just have to say no. You have to let your readers (or some of them) fend for themselves. Here are some situations where it's probably best not to respond privately:
You Already Answered Their Question.
If you've written a half dozen posts about where to find article writing gigs (given the freelance writing niche as an example), then I wouldn't bother answering that question privately. There's a reason you blog or publish public content, and it's archived. If someone really wants that answer, they can very easily search for it. The only exception might be if your articles are scattered on multiple sites rather than a single site or blog of your own.
The Reader is Lazy
You might be surprised at how many times people email me asking "How can I earn a lot of money writing for the Web?" and other things along those lines. Obviously, there's no easy answer. These are the folks who expect you to give them a step-by-step on how to do what you do--they want to replicate your success without doing any of the real work of setting up their businesses for themselves. I generally don't attempt to answer these questions anymore. All of the answers are "out there" and if people aren't willing to help themselves first, then I'm not going to take my time to do it for them. Now I point them to my e-book if they want a thorough background on getting started.
You Can't Afford the Time
The reality is that you're trying to make a living, build a readership, etc. for yourself. That takes time--a lot of it. There will be times when you honestly just can't respond to every comment, email, tweet, and such. In those cases, there's absolutely nothing wrong with being selective.
You're Being Used as a Crutch
Once in a while a reader comes along who asks you a question. You respond. They ask you another. You respond. They ask another. You start to feel like a private (unpaid) consultant on call at their every whim, but since you've set the standard of trying to be helpful, you don't have the heart to tell them to bugger off. It is OK to stop responding if you're either being taken advantage of or if you're simply being asked to devote more time than can be justified to one person. I'm generally OK with people asking for things like feedback on their site or blog, but when it comes to someone wanting a private step-by-step tutorial on doing something (setting up a portfolio, then finding prospective clients, then wanting help with their query letter, etc.) then it starts to get excessive.
Fortunately there's something you can do to answer these private questions while still making good overall use of your own time - you can turn your answers into posts or articles themselves so readers with similar questions can get the answer without you having to respond repeatedly privately.
Taking time out for your readers is a good thing--and a part of the job. But managing your time effectively so you can stay productive is equally important. Where do you draw the line?