As a Rookie my self, I guess the best advice is go slow take you're time, you can never get out and look to much. Watch out for signs and stuff that are attached to polls. Be careful in construction zones where obstacles are prevalent.
Sometimes you'll be put in dumb situations and you'll have to work you're way through it, but eventually the dumb situations end and like I say at the end of the day no matter how many dumb things happened i.e. late customers, having trouble finding product on truck & a gazillion other things. It doesn't matter. At the end of the day if the truck is empty and you made it back to the yard in one piece then you did you're job and should feel a sense of accomplishment. Hope that helps. Just remember those three things, you and the truck come back in one piece and the trailer is empty then you did you're job and those are the three most important things. Paper work errors which you will make trust me I've made my share of paper work mistakes, heck once I had my bank bag ripped out of my truck had all my checks in it from that days deliveries oh boy that wasn't a good day.
Sometimes the addresses will be wrong that you are give you can insert that into the dumb things that happen catagory.
Sometimes you'll deliver to a customer who isn't really a customer, but half the time most customers employee's don't even know what day of the week it is and they'll take you're stuff. Now stuff like the paragraph above doesn't happen every day, but I had it happen to me today, there are two places on the same street in the same part of town with the same name. One is a customer of ours the other isn't I went to the wrong place the people there were a tad confused, but went "Humm maybe they did order from them you know emergencies and all."
Heck there was years ago I think he's around anymore a guy named moondog who lived in Knoxville, TN and he was a trucker for the now defunct Star Transport of Morton, IL (they were bought out by Swift maybe 1.5-2 years ago somewhere around there.) He had a story on his blog and this doesn't happen often, but he was loaded with a load that was not a Star Load, however he was at a Star Transport customer, but was loaded with some owner operators load instead and the freight brokers had to switch the stuff around ended up being a big mess, stuff happens. I guess my point is be prepaired sales people, truck drivers, dispatchers and warehouse people were all human and we all make bogus time costing mistakes, but as time goes by and you get more experience and the good thing about trucking is, it is repetitive and trust me the first time you're new to someplace or something is a real bear, but the second time you go there, you'll be amazed at how much easier it is and by the third time you go there you'll have it down and by the tenth time you're there you'll know everyone they will be used to seeing you a little and things get a lot easier.