Buyers value your business based on risk (real or perceived) and future cash flow. Consider potential business risks. What could prevent your company from realizing your forecasted earnings? Think talent, customers, suppliers, competition, cash flow.
Strategize ways to reduce risk in each area, e.g. cross training, outsourcing, succession planning, customer diversification, backup suppliers, etc. The more you do to take away potential pain points, the more attractive your business will be.