If you don't do all of these things, then, my friend, your sloth shall be your undoing. If you do take all of these measures, then you're either very wise or you're a non-life-having nutcase who dons a helmet to drive a car. Unless you're a monk or you don't have your system's local administrator or root password, then impatience and a desire to work, create, and play unimpeded will eventually win out.
The solution is simple: Maintain parallel paranoid and promiscuous selves and give each its own computer. Your promiscuous self is open and daring, a slave to impatience, talking to strangers, and too busy being productive and enjoying life online to keep your place spotless and run the neighborhood watch. Your paranoid self regards your computer as a vessel for your electronic soul, your ambassador for official communication, the keeper of your secrets that scorns unfamiliar visitors.
Your physical computer should always be configured like a server, as paranoid as you can tolerate, and like a server, left untouched except by your paranoid self. Your promiscuous self can have free run of a largely unsupervised playground operating in a virtual machine. Your devil-may-care persona's e-mail client has HTML viewing enabled and is configured to access only spam accounts. You run your browser wide open so you don't have to constantly click through barriers to get where you want to go, and you're even free to share files, use IM, run BitTorrent, and host a Web site and mail server. These are facilities you don't even install on the host.
If a physical host is adequately protected, and the virtual machine guest does not use a bridged connection through the host to get to the Internet, then a virtual machine guest cannot harm its host. The only link between the guest and host should be an isolated shared folder owned by an unprivileged user with no log-in access; don't get lazy and share a host's entire drive, even read-only.
If the promiscuous virtual machine gets infected or its trash piles up, the fix is simple as long as you plan ahead. After you finish configuring your guest OS and applications, but before you reach out to the Net, clone your guest's disk image. When things get untidy or unsafe in the guest, just boot from the clean clone, mount the fouled guest image as a secondary drive and copy over the files you need as you need them. Repeat as required. IT people secretly want to implement best practices in the organization and exempt themselves from them. Now you can, too -- without being a hypocrite.