Use a virtual machine to do risky stuff. How to stay as safe as possible?

Question

I have a PC with Ubuntu and Windows in dual boot. I use this PC for basic stuff: Windows for gaming, shopping and common browsing, Ubuntu to do something such as home banking.

I was thinking to create a virtual machine on Ubuntu with another OS that I will use to download stuff from IRC and Torrent and other risky stuff like streaming, because I don't want to risk to get a malware on the main OS.

But I'm still afraid. I know that Ubuntu (as the main OS that runs the virtual machine) is already pretty safe, I also know that Virtual Box does a pretty good job for security, but I'm asking if you can give me any general tip and advice to keep the main OS as safe as possible.

Obviously I need a shared folder to transfer downloaded files from the virtual machine to the main OS, so I can not completely isolate the virtual machine from the host OS.

I was thinking to put another OS on the Virtual Machine because so a malware would have to work on that OS and on Ubuntu (the main host) to infect me (and it's pretty rare to get a virus that runs on 2 different OS and that exploit Virtual Box), is that a good thing to do or is it useless?

This has been marked as duplicated because there are these posts:

• How secure are virtual machines really? False sense of security?

• Hardening VM for Malware Analysis

• Is it possible to make my host completely safe from the virtual machine (where I will do malware analysis)?

but it's not the same thing I'm asking. I'm not gonna use the VM for Malware Analysis, so as I said in the post, I can not isolated it, it has to be internet connection and a shared folder, so mine is a different question.