Personally, I started out working as a VLSI engineer and built some semi-technical web-based tools as a hobby (DNS, whois proxy, that sort of thing). That hobby work - which involved building a product, deploying and running that product, and interacting (usenet, mailing lists, IRC) with other people working in the same space - led to professional work. That was what would probably be described as dev/ops these days - designing a network, developing glue perl scripts to hold a system together, doing basic DBA work, web scripting, monitoring scripts, working out why database replication had shat itself again, that sort of thing.
All of that work was on unix-ish boxes, but none of it was *about* linux or unix. These days I run my own company, and get to do pretty much what I want to do, as long as customers are happy. That mostly involves developing product design, implementing, QA-ing and deploying it. Then maintaining it and doing customer support for it. (Yay, small company!). I couldn't do that if I weren't reasonably fluent in RHEL, Debian, Solaris, OS X and Windows, but there's probably not more than 2 or 3% of what I do that's OS specific.
Unless you want to be a junior sysadmin or a low level programmer, you're never going to have a job where the operating system is central to what you do. It's always about business goals, politics, network architecture, balancing how much you spend on different parts of your network, and different parts of your company (skimp on dev, get burned on ops... skimp on marketing/sales and the rest of it doesn't matter...). The fastest way to learn that by working with good people, in a flexible environment, one where you can find stuff that needs doing - and that you think you can learn to do - and adopt it as your own.
The best way to get that sort of position is a mixture of demonstrating that you can do "stuff" (write scripts and share them with the world, work on an open source project - write documentation, at least, deploy an interesting website) and that you can work with people (interact - usefully - online in IRC or technical mailing lists, work on an open source project, write docs, improve tutorials, help others).
And give up on the focus with Linux, unless you're planning to be a software developer in a niche industry (embedded design or driver development) or you want to be a junior sysadmin forever. Focus on what you want to accomplish, not the OS.
If you want something concrete - if you're planning on starting out via the sysadmin route, learn perl. And maybe virtualization (ESXi, most usefully). If you're thinking software development might be interesting, learn python and SQL. Whatever you're planning, design and publish a website, with something of interest to you on it, running on a cheap VPS somewhere - register your own domain, run your own DNS, run your own email. Certification - in anything - isn't a magic key. Generally it's something you'd pick up as "career development" when an employer is paying for it, and it's a very rare certification that teaches you something you can't learn other ways, and a fairly rare one that's taken seriously by hiring decision makers.
Do something. Network. Be prepared to work for cheap, if it's on interesting projects where you'll learn. Do *something*. A decent resume, a web presence and a github repo with something in it won't hurt at all. Socialize with people who are doing things you might want to do. Go to your local Linux users group. And your local Windows users group. And your local perl / python / vmware / sql server / postgresql users group. Play nice with others. Show up for things you're interested in - and stay to help out with the cleanup.
