I don't think there is any need to make use of any VPN to make trade unless you have something to hide, I just login with my PC to a trusted exchange and begin to make my trade though I made sure I have a very good antivirus installed in my PC so that I won't be hacked and my coin stolen, I think you have to do same when you finally get your system.

You should also make sure that you activate 2FA in the platform you are making use of in trading this is very important than even trading itself.