A good brand strategy is crystal clear, strategic yet operative and, last but not least, simple for everyone to understand. It sounds easy but in order to create a strategy that meets those criteria one needs to work hard. First, let's discuss what the strategy should contain. As I see it there are four 'must haves' that describes what ambition you have for the brand and what the brand is and isn't to everyone that works with the brand:
1) Brand Vision and Goal
The brand vision is your statement of intent for the brand long-term. The goal is short-term, the goal for the planning period.
2) Market space
This describes what market the brand acts in, the consumer or customer needs that it should meet, the consumer or customer segments it should be relevant to, the situation in which it is relevant(i.e. if the situation is important to your brand, for a beer brand the situation is likely to be very important) and the key consumer or customer insights that your brand positioning is based on. To write this down in a crystal clear manner often requires serious amounts of thinking and insight work.
3) Brand Positioning
This is where you explain the fundamental building blocks and essence and values of your brand. I've written about the most common building blocks of a positioning before. Look here
In addition, if you write a strategy for an umbrella brand you probably need to include information about the portfolio brands with regards to their individual positionings and how the brand family works as a whole to achieve your goals.
4) Brand Expression
This is all about how the brand is expressed in the market. Your strategic thoughts on innovation, channels, communication, packaging, packaging design and more. Of course you cannot and should not be extremely detailed here - it is more about providing a picture that makes it clear what overall actions you will take during the planning period in order to achieve your goals and work towards your vision.
As I said, it sounds so easy but it really isn't. Let me know if you think I haven't covered anything regarding this topic that you think I should've included. And remember, based on your company circumstances and ambition level you might be able to develop a strategy in a few days, but often it takes months...