I've worked in the machine-trades all my life, so it's never been a big thing for me. No one, or at least, very few people working in a machine shop even notice a tattoo.
That sorta changed about 20 years ago when I started selling things made in machine shops rather than actually making them, but for the most part, having tattoos gave me cred with the shop-guys, and didn't freak the office types too much. There were/are some accounts where I keep my sleeves down and my suit coat on, but not too many.
Nowadays, I see doctors, lawyers, accountants, you name it, that are sleeved or heavily tattooed. Personally I believe that most people have gotten past the irrational fear of tattooed skin. I know some jobs have poolicies against visible ink-believe it or not, McDonalds doesn't allow it! Mostly though, I think you can get away with a few inches of sleeve showing from the rolled-up cuff of a decent dress shirt.
Personally, I think it's a mistake to sleeve yourself in at an early age. But that's just me-could be it's fine for everyone else. I always looked at tattoos as a sort of milestone, or souvenir of my life. When the time came that I had enoug of them on one arm to look better connected, I had it sleeved in. Getting ready to do the other arm shortly.
Again, that's just me, but I'd say pick out or design something you really like, and get it put on. When you see or dream up something that sorta-kinda goes with it, put that on, etc.
Just seems like doing up your arms completely at, say 24 or 25 sure takes a lot of good times out of the picture, and locks you in awful young.
One more time-that's just me! My opinion isn't worth anymore than yours is.