Congratulations on the new job! Its a good one which you should enjoy (most of the time!)
A few practical things that come to mind...
Try and be aware as best you can what's going on around you with regards to the turnaround. Make sure the pax staff have called the flight to the gate, know what stage the loaders/cleaners/crew are at, find out the latest slot time and communicate this to the crew and push back team etc.
Be nice to people! Plenty of guys who walk around with 'Dispatcher' emblazoned across the back of their hi-viz think they're God's gift and have free rein to tell people what they think of them. Everyone is as important as everyone else, you are all on the same side! Having said that you can be faced with a bit of abuse of other staff, crew and loaders (ie asking them to offload a bag in the middle of a 757 hold). Take it on the chin, its not personal.
Have a pen (duh), an accurate watch, and a mobile on you all the time... Radios never work when you most need them to.
Get bag counts as early as possible; its much better knowing you're a bag up 10mins before departure than when the thing's closed up and ready to push.
Be firm but fair. Rules are rules, but you'll get to know when its acceptable to bend them slightly.
Don't be afraid to ask someone more experienced if you get a bit stuck; most are more than willing to help out. Don't try and wing it yourself or you may end up causing more problems.
If possible have some figures ready for the crew, ie expected pax load and PRMs for the cabin crew, weather/EZFW/Flight plans (if applicable) for the flight deck.
Get a good alarm clock for the earlies
Just a few basics, most of it pretty obvious but key to ensuring things go to plan and everyone has a smile on their face.
Oh yeah, sweet talk the Purser... You may even get a cuppa out of it!