Are you using hot shoe flashes or strobes externally?
How many flashes, strobes are going to be used at once?
What will you be shooting???
90% of the time, you will not want to use the on camera flash unless you have a bracket for it. You better off using your triggers with the flash in manual mode.
I made a huge mistake and started shooting with off camera strobes with multiple strobes at first. I started with three lights and this made it very difficult but I did get it down pretty quick. I should of started with one light and Im sure I would of caught on quicker. You will be VERY amazed what one light can do for you and how easy it is with some ambient light also. The key is dragging the shutter at times so you need a steady hand and a subject that is stiff.
The OneLight Workshop by Zack Arias is a GREAT place to start. I really like this guys style and his DVD.