Read a lot about budgeting before actually done one. Here are some things that proved right for me:
Worthwhile to know:
Workout concepts before running Excel. The most important one: limiting factor - the starting point. In 95% of commercial entities it is Sales.
Knowledge of the operation model. Necessary ingredients for this is research on the industry, close relations with technical staff and time. Time for digesting the first two. Time to let brain forget all noise that was so inspiring about the topic and focus on the basic.
3.Historical information is required. The budget without historical information is just another spreadsheet that works for one meeting. If historical information is not available start collecting it - it is the first step of budgeting
What do I love about the budgets? When they make no difference.