Finding customers is always a tough task. We started from μ-ISVs with simple Windows applications to probe the market and see whether people are ready to buy tests and QA as a service and then slowly expanded the offered services list.

We have great customer retention (excluding some specific one-time projects, like a penetration test), I hope due to our dedication :)

I would say manual tests are most popular, and then load tests, then automation. Often customers start from a tiny manual test and then use our services more and more, in other QA areas, being happy to receive all of those from one window in a unified manner.