While technically you can help people who live anywhere, people are scared send precious photos away and clueless about getting photos scanned properly, so your best bet, if at all possible, is to start building a reputation locally. The testimoials and "before-and-afters" from locals will be impressive on your website, and will encourage other customers to either trust you with their photos, or to make the effort to scan their photos properly for you.
What you'll need is to do some research into the market for professional restoration, the competition, and the amounts that people are willing to pay. Then you need some capital and time for all the promotional materials you need: a strong, professional website, business cards for the locals, and the time to become a part of a few social media communities, both broad and focused.
Remember -- the enemy of home-based businesses is undercapitalization! Go in with enough money to promote yourself!
I know a guy who as I recall started out retouching old photos and branched into creating digital fine art derivatives of photos (e.g., digital sketches). I believe he does rather well, but it's taken him a long time to become well enough known (more than 15 years) that people seek him out.
Some very rough thoughts off the top of my head:
- Figure out what your inputs and deliverables are. You may have to offer a number of options.
- Create a great web site with very visual examples. Then (this is the hard part) try to make yourself known amongst your potential customers. Keep in mind competition is quite stiff online to get people to spend money. People have to find your great web site.
- Figure out how you're going to manage the eCommerce. Determine your tax situation.
- Don't undersell yourself and don't underestimate the amount of time it can take to create professional results.
I started my own business about 20 years ago as a wedding photographer which I did for about 5 years and did quite well, but realized this was not really what I wanted to do. So I stopped doing weddings and concentrated on commercial and event photography. Very different clientel and was really like starting from scratch. The wedding business really came to me through referrals - more than valuable so I worked on getting the word out and one of the approaches I took was to join a professional photographers association. Most of the photographers there were wedding and portrait people, so as that was my bag they referred the clients to me. So maybe that is something you might want to consider. It's basically free advertising and 90% of my work comes through referrals.
Photo restoration is an art, I have dabbled and done some work for customers but given the amount of time it took to fix an image and what the market will bear price wise meant I would be working for way less than minimum wage. Problem is many folks who do photo restoration scan in the US and send the images overseas for repair and retouching where working for less than a dollar an hour is acceptable - not for me.
What I did was set an annual goal for income, figuring in take home pay after taxes, insurance and medical and then look at the hourly rate you need to achieve that income - gives you an idea of how many hours you have to work and what you need to charge on an hourly basis or on a retouch basis
And as Noel states mentions - dont sell yourself out
Feel free to come back if you have more questions