Today, I work through referral only, do not advertise or have a website. I had a telephone ad/listing years ago and it was too much of a hassle with people looking for free systems or the absolute lowest price. Now, if someone calls me they have some type of a connection with an existing customer and that works well for me. I don't want to waste my time quoting jobs that are likely not going to happen.
When I get a call from a potential customer I try to screen the job over the phone. Monitoring of the alarm is required if you want me to install or repair. I don't install or repair local (bell only) systems. In addition to state licensing, I make sure I have a business license on file with the jurisdiction where the customer is located. If not, I'll pass on the job and suggest the customer look elsewhere. I refuse to do work in certain jurisdictions due to the outrageous cost of their business license. Sometimes the distance is a deal breaker, I don't install or takeover systems that are more than an hour away.
I try to give a wide range of cost over the phone, but reinforce to the customer that it is not a definite or accurate price because I've not seen the job site. You don't know what type of job you're dealing with until you go look. In many instances, this will save you from wasting your time as the customer may have an unrealistic idea of cost. I let them know on the phone, before I go out, what to expect about my process of quoting, contract signing and starting work.
I visit the site and do an assessment, but do not quote the job on that visit. Some people want to know a "ball park figure" and I give them a wide price range, but nothing definitive at that time. This is usually discussed on the first phone call (see above paragraph). I never try to do a quote on the spot as I've found that putting some time between the visit to the job site and the completion of the quote will give me time to prepare something fair for both the customer and myself. Preparing a quote on the spot will likely cause you to overlook something which might cost you time and material.
I get an email address from the customer and email a quote. If they choose to have me do the job, I prepare the contract and all the other required documents (3 day notice, etc.), with a projected start and completion date on the contract. I return to the customer's home for signatures and this allows another look at where devices are to be located. I start work on, or shortly after, the date specified in the contract, which corresponds to the date listed in the 3 day notice.
This process works for my business model, it may not work for you or others.