Don't ever be afraid to ask for help. Even the most seasoned dispatchers can be overwhelmed with things at times. If you feel like you're getting buried, speak up BEFORE it becomes a problem. If you're dealing with 5 guys in the hold, 2 diverts, a half dozen reroutes, and both phone lines are ringing, you are in the red.
Also, don't be afraid to say "no" to something you know isn't safe or legal. Your certificate is attached to every release you send, which means it's YOUR ass on the line, not the dude with the tie that bellied up to you and asked you to do something questionable. You have a responsibility and a legal obligation to shut something down if you or your captain believe something is unsafe.
Always have an "out". If you at any point in the process find yourself saying, "We'll hope for the best", STOP. We don't operate on prayer. If you're enroute somewhere and your plan is rapidly going to hell and you can't come up with another plan, end the mission. Even if the pilot is feeling heroic and wants to "take a look", remember you see things he doesn't. You don't ever want to find yourself in a situation where you're guy either lands or flames out. As DispatcherSam noted, you do NOT want to be on the news.
Sometimes the only winning move is not to play. There will be times where no matter how hard you try, you can't come up with a plan. Winter in New York, everything for 500 miles is at alternate mins or below and expected to get worse, and you're trying to stuff a CRJ-200 in there. This isn't a good place to be...
LISTEN TO YOUR CREW. They've been flying this airplane far longer then you have. When you do your jumpseating (and I suggest doing more than the required 5 hours a year when you're a rookie) ask questions. A lot of questions. Talk to the ops agent on the ground. Talk to the rampers if you can get to them. Talk to everyone who you deal with in the field. Understanding how things work in the real world will help you make more logical decisions when you're in your office insulated from it all. What actually happens when you ask the fueler to bump up the gas 10 minutes before departure? If your company offers you the opportunity for "a day in the field", take it. Working side by side with the boots on the ground will open your eyes to a whole new world and a better appreciation of how your decisions effect everyone.
As Faceman said, a good dispatcher is a creative dispatcher. THAT BEING SAID, as a new dispatcher don't try to be TOO creative unless you're sure it's legal (and something the FSDO won't take a dim view towards, eg. the old "change destination with alternate as original destination and then divert to alternate" trick... Expect an unpleasant phone call if you do this...) A good exercise when you've got down time is to run through scenarios in your head and try creative ways to solve them.
Here's an excellent example that may or may not have happened yesterday: Guy going from MDW to FLL. FLL weather is clear and a million and ATC has a flow control program into JAX Center. Because this is Florida and the sun is still shining, the obligatory alternate of PBI is added. Suddenly out of nowhere a bunch of holds pop up for MIA and FLL and hero find himself in a hold just north of JAX with an EFC of 1 hour. No chance of making that EFC with the gas, but you can't help but notice that the hold stack is being worked down and FLL is taking arrivals. Looking at the trend you surmise that the holds will be cleared shortly, and yet ATC isn't playing ball with you and is holding you to the 1 hour EFC. You're down to bingo fuel. What do you do?
