I think you will find that in answering all these questions, you will be in a better position to take the next step. So now you know where to start, and once you have tackled these questions, the next step is to find examples of devices with similar functions and study them for ideas on how yours could go together. This is the part that takes a fair bit of time. There is no alternative but to put that time in, by finding books, magazine articles, websites, repair manuals for similar devices, and part manufacturers application notes and studying the hell out of them. Once you have something sketched out on paper, like a schematic, you will be in a better position to ask for a bit of help here again. As a preliminary step, you might also consider drawing a detailed block diagram of the different stages of your electronic circuit and show it to us so that we might comment on it. I hope you know how to do a block diagram as this is the most common graphical form in which to share your design architecture before getting down to the nitty gritty of a detailed schematic.