If it is accessible by Tor, I would like to use Tor.
If it is not Tor-accessible, I would like to use VPN.
If Internet is good, I would like to use both VPN + Tor because it's best if I always use VPN, then if necessary, I use Tor as another layer for privacy. I believe that it is a good habit on Internet because if I don't always turn VPN on, perhaps I will lose my privacy when I am careless.
Using multiple solutions at the same time is not always an improvement over strictly using one solution however. In many situations, it only complicates and actually creates loop holes and flaws.
For example. Using VPN and Tor at the same time will be a big disadvantage because of time stamps correlation. Anyway. The only reason I would see someone using VPN before Tor is to hide that they are using Tor from their ISP, but there is the bridge option particularly for that situation. And it would be a really bad 'second layer of protection' because it does not really protect you from any thing. In fact it makes more problems. Your Tor traffic now going through a VPN which is REALLY bad.
Whonix has a great article about the risks of combining VPN and Tor (
https://www.whonix.org/wiki/Tunnels/Introduction). I am pretty sure Tor Project had one or at least a statement at some point but I can not find it right now.
From the Whonix article,
In the User → VPN → Internet configuration or User → VPN → Tor → Internet configuration, anonymous payments with Bitcoin, cash and other methods does not improve anonymity because a user is still connecting to the service from their own IP address (which can be logged).
In the User → VPN → Internet configuration or User → Tor → VPN → Internet configuration the use of shared IP addresses does not confuse modern surveillance systems which have a many additional fingerprinting methods (like user agents) to identify persons of interest.