You may regard this as general advice yet is is not as trite as you may think. The reason is that your question is very general and can be easily be answered by 'that depends' and 'how long is a piece of string'. To answer the vital questions that lead you down a journey of what you should do, you need to go through a Business Planning process. That process provides you with the functional steps you are after. The Business Planning process helps you to explore necessary avenues and to ask the right questions. Your first port of call is to research. Some ways (not all) are to look at the current environment, look for models you admire and look for gaps and ways you can be unique. Look at what the market wants. What is the burning problem they experience? Envision with clarity about what you really want to achieve. Is there a match and how can you match the market need? Is there demand? (Creating demand for something new is extremely expensive in terms of time, energy and cost. Oh how I lived this problem!!!). Or can you piggy back off current trends? To answer this question it would take consulting of $5-10-50k of work.

Facebook thrives on fresh, entertaining, highly targeted even quirky content. Since many on FB are not in the 'ads' frame of mind, you need 1. creativity & originality, 2. high emotional appeal & 3. a psychographic-heavy approach in your ads. #1 & #2 die quickly with ad frequency & reach