Ah, I remember writing an old Virus guide back in GMod Tower (I think it's the second guide I've ever written). I've since hidden the guide since GMT shut down. If you want, I could unhide it for a bit and post a link. I took a look and this guide is pretty good; it goes over pretty much everything I'd hope a basic Virus guide would. Here's a few things I noted when I read your guide:
You might want to add ammo counts to the guns, just as an additional detail.
You should probably mention that all survivors have the same loadout.
The sci-fi handgun's shots are meant to bounce off walls multiple times, but due to a bug that feature isn't working.
You seem to think that staying in a group is the undeniably best strategy, but there's merit to going off on your own or in smaller groups. If the infected break a large group's defenses, there's a much larger chance of being infected if you're near them. Plus, infected generally target larger groups more frequently than smaller ones because that's where everyone is. That doesn't mean that being in a small group is necessarily better (it's easier to be overwhelmed or flanked, for example), but it's just something to keep in mind.
You might want to add more pictures, just to break the text up a bit.
Just pointing these minor things out.
Anytime the Tommy Gun is mentioned: "TommyGun" -> "Tommy Gun"
Tommy Gun: "with it's large" -> "with its large"
Plasma Autorifle: "kill a infected." -> "kill an infected."
TNT: "chased, it's radius" -> "chased, its radius"
Adrenaline: "hordes a must use" -> "hordes; a must use"
Anytime there are parentheses in a sentence: "here are words(little aside)" -> "here are words (little aside)"