People always asked me how I started blogging and why I felt it was okay for me to blog. First of all there are a couple different roads you can take: you can either blog on a personal site or you can blog for money. I've done both. I started blogging on a personal site several years ago and a lot of it was what I was doing in my off time, even some home lab stuff. I only wrote a few before I saw a call for writers from TechRepublic.com. They saw my personal blogs and said I would fit in.
The problem with writing for a paying blog is that you need to come up with content at least weekly usually. So if you are a sys admin, this can be easy because you never run low on diverse material. When I was no longer a sys admin, this got harder so I moved on to blogging for VirtualizationAdmin which is a little less stringent on the weekly content.
No matter what, you probably have something to say. You've probably run into one problem or another that other folks are running into and would love to read how you solved it. I highly recommend starting your own blog and if you're still excited about doing it after a while, start publicizing it on Twitter or LinkedIn...any of the social media sites. If you're interested in getting paid for it, start looking at the sites you like to frequent and see if they're looking for writers. It's a great way to boost your career and an even greater way to basically build your own KB. I can't tell you how many times I just Google something I know I've written about but have forgotten.