Hmmmmmmmmmmmmmm............ I've done it for other business. I'm not a photographer by trade.
But, even without reading the article, that photographer is saying +25% in business, let's say that's the same time frame as his $120K increase in business, to be safe. That would mean his business started with a 6 month revenue baseline of, what, about $400K, which means he was doing about $800K a year already? Really? If so, that's pretty big for a photographer already, isn't it? (If true, it meant s/he already had a few thousand customers, right?)
Do you find that credible?
Here's the rough math on DM.
You will have to acquire a targeted, validated mailing list.
You should expect a 1% hit rate, 2-3 if you're really doing well, where a 'hit' is someone inquiring about your services. You might close, as business, 1 in 5 of those, or 20%.
That would be a success.
So, say you do weddings -and- have all of the staff to handle the increase in business. Each wedding is net profit of $1K, just to make the numbers round.
If you wanted $100K more profit, and you'll have to do the math because I'm in a lounge now, how many direct mail pieces would you need delivered to do that?
x items * 2% response * 20% close = $100K. Profit. If and only if your list is 100% exactly on target, and 100% valid addresses.
Your list for mailing will vary in quality. Figure about 1/3rd of what the list seller says will hit a target.
So, if each list costs you $1K, and you need three, and you have to send a couple hundred thousand mail pieces at ~$1 fully-loaded cost per piece, does it make any sense to you?
That means you need (a) a cheap list which is (b) right on target matching your exact services.
That may be possible. There are specialty magazines which do list rental, which is to say you can have THEM send a piece to all subscribers, maybe as a blow-in. That might work. But if you were going to try, talk to references who have done it before.
..........
It occurs to me that the article you read is short on details because it isn't true.