Most cafe owners I know have a vision of what they want their cafe to be. Its in their head. If I was to give one piece of advice to anyone before they consider to open a cafe, it would be to create your vision.
Yes there are loads of other really pertinent issues you need to consider but before all that.. before you get caught up in the how will it run, who will I employ, what will it turnover - you need to figure out what this cafe is going to be. This, is the only place to start.
Map out on paper what you would like your cafe to look and feel like. What message do you want it to communicate to the customers. Then figure how will you communicate that message through everything you do. What values will it stand for. You build everything around this from the toilets to the menu. Let this be the core of everything that your cafe will stand for. Remember, a business is an extension of its owner. It represents you. Without this core and vision you have just an idea. The same idea as everyone else who just wants to open their own cafe. Worse, you have an idea without a plan.
Once you know what you want to achieve, get some ideas and create your own footprint. Don't replicate someone else's idea - because that hasn't come from your heart. Its not yours, its an extension of someone else. You'll tire of that. Innovate and you'll never stop innovating. Create something new.