Forecasting model

I have done some forecasting but it's been a while and I have to refer to a reference on my bookshelf at home. Exactly what is the nature of your data? Do you have a list of every trip with date/time for the entire year? Do you need to forecast the number of trips, or also take into account the duration of each trip? Is your goal to forecast how many drivers you need over time? How granular is your seasonal variation--do you want to block it into months, weeks, days?