The life of a solo entrepreneur sounds appealing: You get to do things your way and set your own schedule. You know your success or failure is fully due to your efforts. But there are downsides, too, such as a lack of institutional support -- and, of course, finding your own health insurance.

One of the challenges many would-be solopreneurs overlook is cash flow. When you -- the owner of a single-person business -- stop working, your cash flow's often reduced to zero. But you also don't want to feel you can't take a day off: What's the point of the freedom to set your own schedule if you can't actually enjoy it?

Finding ways to manage cash flow should be a top priority for solo business people. Fortunately, there are a few ways to optimize yours:

1. Pinpoint the source.

Cash-flow problems come in many flavors. Take a look at your books: Are you simply not making enough sales? Try investing in a lead-tracking tool, which can show your team where leads stand at each point in the sales process and help you automate communications according to the prospect's stage in the funnel. If you have enough accounts, is your typical transaction smaller than you thought it would be? Upselling existing customers may be your best bet.

For a surprising number of small businesses, though, the issue is that their accounts simply aren't paying on time. Intuit data published earlier this year showed that a third of U.S., U.K., Australian, Canadian, and Indian small-business owners have more than $20,000 in outstanding receivables. Nearly as many, at 31 percent, wait a month or more to get paid by their customers. Although relationship building can help, a different payment model may be in order.

2. Rethink your payment model.

If the same accounts are late to pay each month, consider switching to a subscription model. In an Insights by Stanford Business interview last year, Zuora CEO Tien Tzuo argued that every business will soon be subscription-based, a model that's grown by 100 percent per year in the past decade.

Why are subscriptions so popular these days? According to DealMachine CEO David Lecko, the reason is twofold: The subscription model decreases the consumer's barrier to entry by reducing his or her upfront cost, and it gives the provider a more predictable revenue stream. In effect, subscription companies never start a month with no cash flow.

3. Shorten your invoicing cycle.

What if you've got a subscription product but still struggle to collect payments? Try sending invoices more often. In his payments guide for freelancers, Brennan Dunn suggests that solopreneurs invoice their clients once a week or more. Although that might sound like overkill, especially if you're used to sending monthly invoices, it's a good way to put pressure on late payers.

Remember, most companies work on net-30 terms. If you invoice once a month, you have to wait up to 60 days before you can consider an invoice outstanding. Not only do you get paid every 37 days (or fewer) when you switch to weekly invoicing, but also your invoices will pile up much faster. Multiple outstanding invoices get attention from corporate accountants in a way that a single delinquent invoice simply doesn't.

4. Get a carrot and a stick.

Speaking of getting accountants' attention, penalties and incentives are great ways to promote regular payments. Accountants might ignore a begging email, but they won't ignore an email when money is on the line. Start with perks before sharpening your stick for persistent nonpayers.

A common payment incentive is known as 2/10 net 30, meaning that the client gets a 2 percent discount if they pay within the first 10 days of their month-long payment window. If that doesn't work, institute a 1.5 percent interest fee on outstanding invoices. Invoice the client as soon as the job is done, and put the due date at the top of the invoice.

Every solopreneur has short months, but they should be few and far between. Don't let cash flow stand in the way of your success. Get out there and make some more sales. Consider swapping one-off work for subscriptions. Crack down on late payers, but be careful not to drive off their business. Do what you need to do to build a healthier bottom line for your own business -- not just others'.