To put you at ease, it is not uncommon to start up a business without a strategy or KPIs (key performance indicators) - yes, it sounds strange but you can actually still do well at the start without a strategy or KPIs. But it doesn't last long. Soon you will need a strategy in place. So you have asked this question at the right time.
I'm not a financial professional but a marketer and business owner. My recommendations may be marketing skewed. But there's one thing I strongly suggest financially - engage a management accountant who knows how to work out the cost of producing your work, cash flow and pricing strategy. On the marketing side of things, here are KPIs you must have in view:
1. Are you working with your ideal clients (some things you want to consider here will include: are you feeling recharged every time after you finish a client's work, are you driven to do you best for the client)
2. How are you referred to in the market by clients, in other words, how are clients describing you and your work
3. Is your work producing the right balance of creativity and desired impact, that is, delivering the intended message
4. Your sales cycle process - how long does it take before a client say "Yes, you're hired!"
5. Are you hitting the right profit margin
Hope these help.