Hi i am writing my business plan, I have identified my potential revenue streams such as;
1) Ticketing and Merchandising
As well as a few others, however how do you go about predicting how much you will make from them, what is the rule?
There isn't a general rule. Your company is unique. Your unique value proposition to your customers will be priced in a way the reflects the value you add to them. As such your per unit sales -- and life time customer value will be unique. The market you are in will provide benchmarks for you.
That being said -- you need numbers in your spreads of your business plan right?
So focus on revenue source #1 -- since these are the customers of your primary product. The second is a separate product with a different customer. Allow that to be "frosting on the cake" if it emerges -- but build your business plan around providing one product/service to one customer group.
On the ticketing and merchandising -- you need to make a set of assumptions. How many people visit the store. What percentage of them make a purchase. What the average purchase it. These assumptions need to be based on a couple things -- among these are:
As I am sure you can tell, this is a lot of work. There is a short cut -- having a track record and extrapolating. "We have done this for this amount and with an infusion of this we could do this projected amount." By implementing and developing a model you will have factual numbers that can be defended. Then your projected financial numbers will mean something -- far more than the pixels they were concocted upon.
I am sure you will here it from many -- there are hundreds of award winning start-up business plan collect dust on the basement and attic shelves. Why? Because they were not written iteratively with implementation. Make your business plan a living breathing document. Start doing. Document what your tracking numbers are. Make them the basis of your business plans projections.
Good luck --