أنشئ حسابًا أو سجّل الدخول للانضمام إلى مجتمعك المهني.
Though I do not have practical experience of forecasting, a theoritical answer would be
1. Using multiple methods of forecasting
2. Comparing with sales data of previous year and analysing with current market conditions
3. conducting test on sample and extrapolating it for larger audience.
