Get Lexicomp for your smartphone. I have been a hospital pharmacist for almost 6 years now. Having that amout of information at the tip of your fingers is invaluable. Don't worry about the cost of the subsription. Trust me, it's worth it! Also, when you come across something new or unfamiliar, go back and read up on it. I know it soundsl ike pharmacy school advice but you will come across alot of weird stuff so it's best to learn as much as you can.
Finally, learn the computer system inside out. Not just from your perspective, but from the nurses perspective as well. You will be bombarded on a daily basis with questions from nursing, so try to get a feel for what they have to deal with (ie their Emar interface, barcoding, etc).
Lastly, don't stress. One thing I have leanred is that it is very rare to have a doctor or nurse ask some super random clinical question. This isn't pharmacy school when your preceptors drill you about detailed mechanisms of action, molecular structure, statistical tests etc. You will be surprised at how much you actually know!