I hear Effective C++ is a must...
Actually, that book rocks me... I have a copy (not in my native language, mind you) and have read it several times, each time finding something I did not realize the first time around.
I found myself in a similar situation some time ago and well, I am no expert but the STL really, really changed my life. Forever. I think you can find some posts around here where I would use my own string and list classes... Well, to hell with them. Take the STL one step at a time, say, strings, vectors, move on to iterators, harvest the power of lambdas and ranged for loops... You can really have a great time with that!. Actually, is not that much different at all, it just feels more natural and really helps you out speeding up your process.
Keeping in touch with new features (there are a lot of them) is overwhelming but all you have to do is take steady, small steps. Incorporate new stuff in your codebase and you will be allright. Get used to read it and tweak it until it feels right. Also, this may come late but I will not waste the chance of saying it: mind the const correctness!!!. Snowball effect at its best.
Edit - PS: Internet forums are your friends... I browse them regularly, just reading, learning and, sometimes, getting frustrated. I think most of us really feel overwhelmed reading guru code but hey, it's ok. Everyone has to start small... Someone up there said about starting with small games. That's all about it I think: starting small, getting in touch with people having the same questions, living and learning. And in my case, of course, ending up at square one :P.