If looking for a VPS, it's important to know how much memory, storage and CPU power you need.
Once you've got your desired specs nailed down, look for, KVM servers, these are essentially the best performing servers.
I would certainly consider checking if the provider is an actual company, or just a plain-face website - this will help with ensuring they're a reputable firm.
Also, don't forget to request IP addresses from them to check IP trust ratings, there are honestly quite a few things you should always check, and these are just the very few.