It's not an art. It's simple logic. Don't point motion detectors at windows, stairs or stuff that's going to cause problems. Do place motion detectors where the thief is likely to move, such as a bedroom hallway, the vicinity of the hi-fi equipment and, for most of my customers, near the computer.
I can and do explain that much over the phone. Your average primate knows what a window or mirror looks like. :^)
Smoke detector placement is simple enough in the average residence. Don't put them in the garage, furnace room, attic, kitchen, etc. Do place at least one on every residential level (ie, not the attic), at the top of the stairs and at the bottom of the basement stairs. Place one within 12 feet outside bedroom doors but stay 5 feet (a bit more than NFPA minimum) from bathrooms with showers or tubs, laundry room and kitchen. Stay away from air vents. On new construction and wherever possible in existing homes place a smoke in each sleeping room.
There are other issues such as sloped ceilings which I determine over the phone.
I can learn as much as is needed to spec a fire alarm system for just about any job without ever seeing the premises. On new construction and on most commercial fire alarms, I ask for plans. I learned to read prints over 25 years ago and can spec a fire system from them or from architectural drawings when necessary.
You've said a mouthful there. The fact is that I've been spec'ing alarms longer than most salesmen you'll meet and can easily see potential problems that most younger salesmen don't even think about -- without ever visiting the site. That comes with years of planning, installing and servicing alarms. Consider the number of times techs post complaints here about idiot salesmen specifying work that either can't be done or (more often) in ways that no sane technician would consider doing it.
I know that there are plenty of online dealers who will sell the customer anything just to make a buck without a second thought as to the level of protection the client will get. Many employ telephone sales clerks with no background in security at all. Remember that moron who came here bragging that he was selling the finest magnetic contacts in the industry yet refused to disclose who the manufacturer was? It turned out he was pushing Tane (ugh). I try to provide solid hardware and I offer advice based on many years in the trade -- far more than most here. In doing so I'm able to give customers more than just parts.
Not *anyone* -- only those with a bit of tool skill and the willingness to take a little time learning how to accomplish the task. Remember, DIY is probably less than 2% of the security market. The vast majority of clients cannot and should not install their own systems. For example, my father is 85 years old. He has a near genius IQ and a mater's in engineering. However, he has neither the interest nor the willingness to learn how to do the job.
OTOH, there are (and we both know this) plenty of incompetent, uncaring slobs in this industry who should never be allowed to hold a screwdriver, much less pull cable through someone's home. Remember the fellow from California who posted pictures of the damage some Protection One dealer did when they pierced the DWV stack (for those unfamiliar, that's the "poop pipe"). His walls and ceiling were literally soaked with sewage.
It's often better than what some of these nimrods consider a "professional" installation. It's always better than dealing with an online dealer who provides no tech support at all like several of the characters Olson recommends.
Indeed I do. Continue doing the best darned installations you can and taking proper care of your clients. I do the same for my DIY customers. Their jobs may not be the same quality as yours (I prefer to assume the best) but the work will be better than many and much better than a few "professionals." That's not by any stretch intended as a slight to true professionals. But let's face it. Buying a professionally installed alarm system isn't what it used to be. For the customer it's a crap shoot hoping they've chosen someone honest and competent. Sometimes you're the windshield; sometimes you're the bug. Sometimes you're the Louisville slugger; sometimes you're the ball."