1) Can you show me a mock-up to help us choose a designer/developer? No.
I fell for this once when I was young and naive. I made no money and wasted lots of time. Don't do unpaid work for the chance to be paid -- this wouldn't fly in any other industry, so why web design? The best case scenario (though rare) is that you get a job with a client who knows that you'll work for free when necessary. The worst case scenario is that they don't pay you, and still use your stuff, knowing you don't have the legal resources to do anything about it. Most likely though, you’ll just waste time.
2) Can you give us a discount rate? No.
There are A LOT of companies out there that do not see web design as a service worth more than $20 an hour. These should never be your clients. In my early post-college years, I used to value "getting the job" so highly, I would take on an inordinate amount of work for the pay. Let me tell you that it's not worth it. Ever. Remember, you may be doing this company a favor, but on the flip side, you're hurting your own future, and your family's. Nowadays, I give my hourly rate immediately, and it weeds out many potential clients. It's simple math really -- if doubling your rate loses half your client work, then you're still making as much in half the time. If you do excellent work, get paid for it – there will always be comparable "firms" charging double what you are.
3) Will you register and host my site? No.
Sure it seems like a good idea -- free recurring revenue right? Well, maybe... if you can first get them to pay, and then if you can justify making $10 a month for the endless phone support you'll have to give at all hours of the night. You see, once the client thinks that you are responsible for their email and website functionality, you WILL get called all the time when their email shows the slightest wavering or their website 404s for any reason on their home computer. Believe it or not, I've even known someone who had a client call about his cell phone functionality just because my friend hosted his site. Don't do it...it's not worth it. Give them a registrar and hosting company and let them sign up themselves.
4) Can you copy this site? No.
Now you may think that I answer "No" strictly from a moral standpoint, and although that is true, there are other equally important reasons. First, if they're copying a site, they have shady ethics themselves and the chances of you getting paid on time and in the full amount are unlikely. Second, doing this type of work reduces you to a monkey, and although some of your work may be like this to pay the bills, why purposely pursue it? Third, if it's a true copy, the only benefit you may receive is payment - you really won't get to use it for a portfolio or example work, and furthermore, this type of client is one you do not want work from in the future.
5) Can I pay for my e-commerce site from my website sales? No.
I hate to be the pessimist, but when I am asked this, I want to tell them that they most likely won't make any money so they might as well ask me to do it for free. Yes, I know there are exceptions, so sometimes I will ask them about their business, marketing, and revenue plans, which 99% of them don't have. They just thought that selling t-shirts would a novel idea for the internet. I usually go into a spiel about having to support me and my family, and I can't do it with speculative work -- I then recommend Yahoo! Shopping or CafePress, and 9 times out of 10, they never get their site up anyways.
6) I have a great idea. Do you want to...? No.
Not much different from #5, but could be a much larger time waster if you buy in. Again, not trying to be a jerk, but if the person adds little to the potential business outside of speaking an idea, then any work you proceed to do is mere charity (which you may be okay with). But to be honest, I'd rather be charitable with my family and friends and make them partners for free versus a stranger. Trust me, if some really has a great idea, they'll make you partners AND pay you as well.
7) Do you have an IM account? No.
I might give it out if it's to a person I can trust during an intensive project, but as a general policy, I tell clients that it's my general policy not to. The reason here is obvious -- you have a life and other clients beyond them. Many clients see you as an on-call employee, and this is bad. This is why you quit your day job...
8) Can I just pay the whole amount when it's done? No.
I require 50% up front (unless it's a huge job -- then maybe 33%). I need that assurance that they have "bought in" on this project, and that I can plan on the income, pay bills, and eat. People who want to pay at the end are much more likely to back out after you've done tons of work.
9) Is there any way you could get this done tonight or this weekend? No.
Once they know that you helped them out one time, they will expect it in the future. Now you might choose to get extra done at night (I do all the time), but don't start making promises about getting things done at night or on the weekends/vacation. I know a lot of freelancers that charge night/weekend hours as well, so that might be a possible route to take as well. Because the reason you freelance is for the freedom, right? Right?
10) Can I be sure you won't use this work in anything else? No.
This is a very sensitive subject because most clients misunderstand it (intellectual property is a tricky subject anyways). In my Terms and Conditions that I require all new clients to sign, I make sure they know that (1) their code has utilized code from other projects which I haven't charged them for (2) I will probably use code from their project on other projects (3) the own the code and implementation of the project (finished website), but not the actual code pieces (login system, image uploader, etc.). I pride myself in productivity and speed, and I need to use other code all the time to accomplish this. Not to mention that I sell stock Flash which I may need old code to help build. They're not paying you to create code that they in turn will sell, so make sure they know that it's the implementation and not the coding that's theirs.