When people want your advice for free, send them a sample of the work you do; you will be surprised at the relationships you form.
Almost everyone in business would like to have services and products for no cost to them. I work with all kinds of companies from large to small. Every single one of them wants my information and services for free. I only do pro bono work for non-profits and even then, if there is a cost to me, I generally try to pass that on. If you give away your time, then you will be valued at that same price.
I visited a client today that wanted help with some aspect of their website, and I gladly had my colleague come with me to give some instruction. When we arrived, the person needing help was the same one we had given the information to before. As we did not charge on the first occasion, they had not paid too much attention to the process and how to complete the work. The time spent with them today will be a billable item; I do not like to be taken advantage of in any respect.
A good way to get around such a thing happening to you is to produce a sample report that gives advice for free. The only cost to you is the printing and the time it takes to write the report. These reports can also be made available on the website for downloading. The report can be one or two pages of FAQ (frequently asked questions) or a step-by-step procedure that is common to most industries. The point is to make the information available and free up your time to sell and to do the work that helps you make an income.
Getting sample reports is often a misnomer. I have seen far too many of them end up being just a come on to buy a service. The word free is no longer free. There are many ads in Entrepreneurship and Start your Own Business type magazines that offer free reports. The problem is that there are really strings attached. For one, you need to send them your address for shipping. If you do that, the junk mail will start. They are more than likely selling the mailing list and making money from the report. You need to make a decision to truly offer something for free and respect other people