It depends on who's asking.
If it was someone local, or someone I knew a little I'd probably tell them the same thing one of the other posters mentioned (i.e. do some of my work, learn the biz, then go at it after learning, doing a lot of reading, and alike).
It would also depend on what they bring to the table in regards to drive, desire, general understanding of the internet, business models, dedication to keep plugging even when they struggle, work ethic, open mind to change, willingness to learn, and so forth.
This business, depending on what they are looking to do is too complex to take someone with NO knowledge or background from 0-60 in any quick time frame. If you are going to make the investment to take some time out of your day to show someone, you want to make sure they are going to use what you give them, or follow through. Otherwise, it's time better spent working on your own stuff.
I actually have been asked a good 10 or so times from different people over the course of 3-4 months. People who want to break in, or learn it, and always tell me they are, 'a quick learner'. But you can tell after talking with someone a bit if they are serious, or just have a burr in their bum and it will fade as the times get rough.
Which as it's been mentioned countless times on here, a lot of noobs burn out in 3-6 months when their early retirement plans don't work out, or they spin their wheels, and are not making millions.
But back on topic,.. I explain the number of hours I work, and other webby's work to make, or maintain their money. The learning curve of the industry, as well as learning the programs, techniques, trial and error, and ever changing net. By the time they've interupted you a couple of dozen times, and start to see they will actually have to WORK to make the money, they go back to placing tiny classified ads from their one bedroom apartments, or watching infomercials.
