Couple of tips for this specific user group:
Do not use shared folders between VM and host
Use a separate network whenever possible
Work on a physical station and not a VM
Take snapshots with VirtualBox
Use this:
https://github.com/a0rtega/pafish, a demo tool that performs some anti(debugger/VM/sandbox) tricks
Tips credits go to BartBlaze presented in another context on malware lab use, but also usable in this context, I hope.
polonus