I am a marketing consultant based in San Francisco with more inbound requests than I can handle. I am well aware that I could make this an agency, but I am not sure that my margins would support the work. How have other solopreneurs scaled their consulting practices?
Network with people you trust. Sell them your excess leads for a percentage of what they'll derive.
Choose other freelancers, whom you might consider bringing on board if an agency emerges.
This way you have only enough collaboration initially. In other words, you're not compromising your own position by taking on added responsibility. But you retain the option to expand along more formal lines if things go well.
We (many individual marketing consultants and some small agencies) collaborate so that we can spread the workload more evenly and get content written and placed quickly.
In this way each person has their own clients, but they may hire others of us to write or place content. This smooths out the feast or famine nature of freelancing.
We publish on each other's sites and as guest authors on larger sites. Sometimes we just write. Sometimes we just assist with placements - whatever is required to get each persons in our collaboration client's work out.
The safest way to do blog outreach for inbound marketing is to have many writers as well as many domains. In this way we multiply our reach beyond what even many large agencies have.
I have Trello boards created specifically for this purpose. If you would like to see them and have me show you exactly how we're doing this just ask. Or if you like you can join our collaboration and take advantage of what I've already built.
Sounds like you've reached a crossroads - with more business than you can handle you have what many would consider to be a "high class problem".
The key to scaling is to build it in to your business model... With that said:
Might I suggest you start with re-visiting (or, if you've never formally done so - creating) your business model.
Since margins are an issue - you will have to consider restructuring if you are going to be able to scale. How elastic is your pricing structure? Can you viably charge more for your services? Can you offer additional services or products to create more margin via an ascension model or via back-end sales?
Many of the entrepreneurs I work with jumped head first into their start-up without considering what would happen during stages of growth. Those that are successful enough to survive (and thrive) often reach a point where they have to "go back to the beginning" and re-vision their business if they are to mature into a successful business (where you, the owner, build an asset and get compensated by the business for creating it via distributions).
You know how to reach me if you'd like one-on-one help.
In any case...best of luck!!
This ultimately comes down to two things:
1) What's your vision / end game for this business
2) If you do scale your business... will it become more valuable or less valuable?
IMHO, you don't want to start an agency unless you want to enjoy the fruits of a negative cash cycle, dealing with pissed off clients on a daily basis and the very real probability of a difficult earn out period should you ever wish to sell the business.
So, do you want to sell it one day?
The fact that you're contemplating starting an agency means that you're probably offering a broad scope of services, and as a solo outfit... it's impossible to deliver 'everything' unless you consider outsourcing the work or starting an agency... hence your current predicament.
You can scale as an agency, but ultimately it doesn't mean you will make more money or provide a better service for your clients, and if you want a business you can sell in the future you probably don't want to start outsourcing or start an agency.
Sure, you can start an agency, but then you need to specialise in something if you want to scale it effectively and perhaps one day sell it.
The hardest part about being an entrepreneur / business owner...is to say the word NO.
Scale doesn't always = more profit.
This all comes down to your vision.
How you scale is by deciding on the service that you offer which creates the most value for your clients and which makes you the most money / profit.
Once you're there, develop SOP's which you can hand over to a sales team and or a team of resources that can deliver the work on your behalf.
You then spend the rest of your time selling your company and not the service itself.
You'll be happier for sure - you'll make more money (by scaling effectively) and if you do decide to sell you can... and without the hassle of earn out periods.
But again, this comes down to your vision :)
Good luck :)
The normal answer to this question is simply increase your prices until you start losing clients, hire staff, or spread the love and get a piece of the action.
I you form associations with other marketers you should charge up to 30% according to your role. If you have a small roll you could charge as little as 5-10%.
Michael Von Irvin
The Greatest Marketer In The World