If you have a lot of one-time projects that don't turn into long-term clients, it is important to look at how you are offering your services and marketing them. If your clients are happy with your work but don't contract with you long term, or often ask you to do one-off projects at the last minute, there may be something you can do in terms of your marketing plan to eliminate this issue.
Set the Tone for Not Taking Last-Minute One-Time Projects
When someone contacts you for a one-off project, it is important that you take it if it's something you do well and you have the time to do it. However, you don't want to seem too eager to take one-time projects. You want to say something to the effect of, “normally I don't do one-time projects but this looks interesting so I will make an exception if my availability works with your timeline.”
Set Up Coaching Packages to Stay “In Line”
Once you deliver the one-time project, make sure to provide a call to action to offer your customer a chance to stay in line for future projects by setting up a monthly contract. Remind them about how fortunately you were to be able to do this project for them due to a cancelation or other reason for an opening in your schedule, and how that might not happen in the future. Give them a discount for purchasing a set monthly contract.
Under Promise and Over Deliver
The truth is, if you do great work, are able to take charge and create a deliverable that blows your client's mind, you are very likely to end up with a long-term contract with that client. However, you might need to take some extra steps to get there.
Interview Clients to Determine Future Needs
When talking to the client about their one-time project, be sure to talk to them about their entire business. Ask leading questions that encourage them to discuss with you the type of projects that they do on a regular basis so that you can figure out their future needs.
Focus on Building Relationships
Remember that every client is more than a paycheck. Every client is also a human being who likely values relationships over the work. It's up to you to figure out how to build that relationship so that they want to call on you every time they have a project within your niche to complete, and where they trust your advice enough to have ongoing projects for you on a monthly basis.
Identify What You Can Do to Fill Future Needs
After your interview, and while working on the one-time project, think about how you can pitch them a contract that answers their future needs in a way that you are the one who is doing all the projects and they don't hire someone else at the last minute, or worse, ask you to fix someone else's mistakes.
Make Them an Offer They Can't Refuse
When you finish the one-time project, it's time to make them an offer they can't refuse by letting them know the things you identified that they need done on a regular basis that your firm can handle. Send them a proposal and ask for an answer.
People get really busy and they mean to follow up but they just get tied up in their work. Just because someone doesn't get back to you right away doesn't mean they don't want to work with you; it may mean that they simply got busy. You need to follow up with them to offer to take that work off their plate to free up their time.
Remember to focus all your correspondence with the client on what you can do to make their lives easier, make their business run smoother, help them avoid problems and so forth. It's all about them, not you. If they get that from their interactions with you, they are very likely to hire you for a long-term contract. But, you must ask for it.