Get your business plan and a pitch deck worked out before speaking to any investors
Remember that investors want a bang for their buck - so a hefty return and that means a decent chunk of the business
Your plan should focus on the size of the market (potential revenue figures), how you plan to tap that market (GTM strategy), a high-level plan of feature development (how are you going to stay ahead), some proof that you've done some risk and competitor analysis (is there already market validation and do you know your enemy), and that you have some idea of how to reach profitability (can this thing be self-sustaining and when)
Then start looking for investors with a portfolio that includes businesses in that industry
If you're pre-revenue or only have one customer, that doesn't exactly scream traction... most investors will want to see that you're either already generating sizeable revenue ($100k+/year) or that you're able to sign up new customers regularly and reliably and that they don't churn out quickly