"Should I write a detailed and solid business plan?"
I would rather say - NO, you shouldn’t. Why should you mark tons of pages, pretending to have a business plan for a startup which is similar to the one for multinational corporations? It’s ridiculous and obviously will be a waste of your time.
Business plan for a startup doesn’t have to be ideal, solid and comprehensive document. It has to explain clearly your idea, value proposition and business model - that’s it. In other words, business plan for startup includes your vision of your business goals and opportunities, combining risks & challenges, and the ways how to achieve the former and overcome the later.
Here is a great insight from serial entrepreneur and investor Patrick Hull, who answered this question in his post 5 Tips for a Great Business Plan http://www.forbes.com/sites/patrickhull/2013/02/28/5-tips-for-a-great-business-plan/#5946ed0f7b1e in Forbes:
I once wrote an entire business plan with a business partner on paper towels. We recognized an opportunity, but had to write it down and test the idea to make sure it would work (we didn’t have any paper handy, although that didn’t stop us). The plan was just for us, but we still had to see if the vision, the financials, and the strategy were sound. We created that company and it went on to gross millions of dollars a month. In other words, your business plan doesn’t have to be some manicured document in order to make it successful.
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