Start with transparency. The provider should clearly publish corporate details, payment methods, refund rules and a working support channel. If they only show you a Telegram chat and a transfer to crypto, this is an alarming signal.
Ask about infrastructure: do you have your own servers, what CDNs are used, is there a public status page. A good sign is the presence of backup sites in different data centers and SLA metrics.
Finally, evaluate the apps. Check whether Smart TV, Android TV, Apple TV, mobile clients and web player are supported, and whether there are installation instructions. A provider that provides an honest trial and detailed guides is usually confident in the product.