Well...If you plan to make welding a career then FCAW would probably be the most common as far as finding a job with decent pay (right off the bat)? SOMETHING ELSE THAT IS VERY IMPORTANT- Is Blue print reading!!! If you want a job, then you'll want to learn Blueprint reading. It will seperate you from the "just a welder" routine. Almost all shops these day need you to read AWS Blueprints. Just call around a few shops and ask...if they say No, then chances are they work off a sketch on a napkin done in pencil...that's not a career, that's a j-o-b.
GTAW (Tig) almost always pays more, but with more pay usually requires more experience, unless you are a complete natural at it...which I have seen, but not very much of it. It's mostly clean work, as the metals can become contaminated very easily. Usually much more quiet than a large industrial shop. You can build anything from high dollar display stands for upscale stores (what my buddy does, and makes really good money) to building aluminum Mountain bike frames for Gary Fisher?
SMAW (stick) is the "Good Ole' Stand by", we use it for outdoor projects and odd local jobs on our site. SMAW is one of those "good to know" skills unless of course you plan to strictly use that process (then you might want to start there). Alot of "Field" jobs like railroad work, mobile service mechanics, construction use SMAW. Less equipment to drag around (compared to FCAW) and can be used in all kinds on conditions.
GMAW (Hard wire) is big with sheet metal, auto body, small parts manufacturing. Another buddy of mine builds computer cabinets (where all the guts go) for large corporate servers.
Anyhow, as far as "what to take?" go with your gut...I prefer heavy metal! Big fabrication...heavy welds...my primary process is FCAW. I can send you a pic or two of what I have built/welds at work to an email?
Pretty much anything you take will benefit you! Oxy/Act cutting and Plasma will almost always go hand to hand when welding...it is the most common way to cut/prep materials. You may also learn Oxy/Propane, Oxy/Propylene and the list goes on. One thing I did was go to a library and check out a few books on the processes (GMAW, TIG, FCAW) to familiarize yourself with what they are.
Check out www.aws.com
, that has a ton of imformation about the field, and try www.weldingjobs.com
it's a forum where you can ask questions.
Oh...Air Carbon Arc Gouging is something to learn too...theres really nothing to it but practice. The first time I used it I was blown away (no pun intended), it's usually used to take a weld out down to it's root (which means you screwed up) so you don't want to get real good at it
I hope that helps?
If you're curious about my experience? I went to a CC and started out with FCAW because I knew what I wanted to work on. Then as luck would have it I applied for a job with only 4 months of experience in school with FCAW and Blue print reading...and then 6 months later I tested and was Certified "All Positions -Unlimited" as a structrual welder. I haven't looked back since...I personally want to learn everything and anything there is to know. I love getting in there and taking nothing and making something!