Step one: figure out what you actually need for your lifestyle. If you have a home office, for example, will you use it? Or do you actually prefer working at a kitchen table? Figure out what you will use.
Step two: Google or Pinterest to find images of those spaces that appeal. Ignore considerations like space or cost, just use the process to find out what your preferences are.
Step three: narrow down the preferences. In the amazing home office on pinterest, what is it that's really pushing your buttons? Light? Wall colour? Furniture?
Step four: mentally strip back your apartment to bare bones and draw that. The only things you need to keep on the plan are plumbing sites, electrical sites (eg where the oven is wired in), windows, supporting walls, that sort of thing.
Now you get to play. Draw a scale plan. Draw and cut out scale furniture, scale walls and shift things around. Remember that you'll need a meter clearance walk space around everything.