I drive for a pay check.
One thing I always try to tell myself is: "swing wide...swing once".
On left turns this is not normally an issue...it is the right turns that will get you. That is why you will see a sticker warning of wide right turns on a lot of tractor-trailers. Pay attention to that upcoming turn and use the left hand lane if you can't make the turn from the right hand lane. Just watch that mirror CONSTANTLY, because the impatient driver will ignore your turn signal and drive up your blind spot. Always use the most outer of the turn lanes, when more than one is available.
If you come up short on a turn, you may end up backing in an intersection to avoid hitting a pole. NOT something you want to do. So, TAKE every bit of space available to you,,,swing wide, keep going. Coming up short is BAD, BAD , BAD.
Speaking of backing. Trucking industry has a term....G.O.A.L... Get Out And Look. People will do the stupidest of things...like drive up so close, and directly behind you, that there is no way you will see them behind you.
SLOW DOWN. Let me say that again. SLOW DOWN. You will learn to give a bit of extra space between you and the guy in front of you. Someone is going to take away that space, because they have no clue, or just don't care. Just slow down, back-off....especially with on ramps and off ramps. The careless driver will "jump" into that open space you leave.
Hint for backing: Forget all that worry about "everythink is backwards when backing" talk, that the advice givers will give you. The easiest way to back up a trailer for the NEW GUY/GAL is: Put your hand on the bottom section of the steering wheel. Turn hand in the direction you want trailer to go. Your hand on the bottom of the wheel does the "backwards" thinking for you.
I have to hang half my body out the window to see around the exhaust and sleeper, when backing hard to the left....so I TRY to set up for the BACKING by getting as straight as possible. It is a trick you will learn with experience. There are some videos online you can watch, then go practice as other's have suggested.
Friends ask: How can you pull such a long trailer? I reply: I turn the wheel up front...the trailer follows me.
Relax...have FUN. For the most part, that big box will follow you. Just be patient, slow down, and DRIVE. You will make mistakes, you will get yourself into a bind. Just remember you can always STOP. As in... STOP, before things get bent or broken. If it ain't working, don't just keep going, figure out what WILL work.