How can I choose a VPN provider?

Going for one VPN service or another really depends on your needs.
First of all, you would have to think about where it will be used : would it be for personal, academic or business use? You can use a VPN at home, at the office, at your University campus or while you are travelling.
Secondly, you would need to consider what features you will be using and then, choose the VPN provider that ticks all your criteria.
If you are looking for military-grade connection security, then the best option is to go for a VPN provider that offers 256-bit data encryption.
If you are interested in P2P sharing, then the best would be to use a VPN that offers optimized P2P servers.