forecasting--how to?

How would I go about setting up a good forecasting model? I have been asked to forecast the number of calls a call center receives.
I have been starting out by brainstorming potential variables to go in my model. Can someone offer some steps of going from the raw data to selecting a decent model? Also, what models are available? I tend to think of forecasting as being very similar to regression. Is this appropriate even when my complaint count doesn't vary much from month to month (doesn't show an increasing or decreasing trend)?